reviewing literature and studies

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• Literature Review: The What, Why and How-to Guide
• Introduction

Literature Review: The What, Why and How-to Guide — Introduction

• Getting Started
• How to Pick a Topic
• Strategies to Find Sources
• Evaluating Sources & Lit. Reviews
• Tips for Writing Literature Reviews
• Writing Literature Review: Useful Sites
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What are Literature Reviews?

So, what is a literature review? "A literature review is an account of what has been published on a topic by accredited scholars and researchers. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries." Taylor, D.  The literature review: A few tips on conducting it . University of Toronto Health Sciences Writing Centre.

Goals of Literature Reviews

What are the goals of creating a Literature Review?  A literature could be written to accomplish different aims:

• To develop a theory or evaluate an existing theory
• To summarize the historical or existing state of a research topic
• Identify a problem in a field of research 

Baumeister, R. F., & Leary, M. R. (1997). Writing narrative literature reviews .  Review of General Psychology , 1 (3), 311-320.

What kinds of sources require a Literature Review?

• A research paper assigned in a course
• A thesis or dissertation
• A grant proposal
• An article intended for publication in a journal

All these instances require you to collect what has been written about your research topic so that you can demonstrate how your own research sheds new light on the topic.

Types of Literature Reviews

What kinds of literature reviews are written?

Narrative review: The purpose of this type of review is to describe the current state of the research on a specific topic/research and to offer a critical analysis of the literature reviewed. Studies are grouped by research/theoretical categories, and themes and trends, strengths and weakness, and gaps are identified. The review ends with a conclusion section which summarizes the findings regarding the state of the research of the specific study, the gaps identify and if applicable, explains how the author's research will address gaps identify in the review and expand the knowledge on the topic reviewed.

• Example : Predictors and Outcomes of U.S. Quality Maternity Leave: A Review and Conceptual Framework:  10.1177/08948453211037398  

Systematic review : "The authors of a systematic review use a specific procedure to search the research literature, select the studies to include in their review, and critically evaluate the studies they find." (p. 139). Nelson, L. K. (2013). Research in Communication Sciences and Disorders . Plural Publishing.

• Example : The effect of leave policies on increasing fertility: a systematic review:  10.1057/s41599-022-01270-w

Meta-analysis : "Meta-analysis is a method of reviewing research findings in a quantitative fashion by transforming the data from individual studies into what is called an effect size and then pooling and analyzing this information. The basic goal in meta-analysis is to explain why different outcomes have occurred in different studies." (p. 197). Roberts, M. C., & Ilardi, S. S. (2003). Handbook of Research Methods in Clinical Psychology . Blackwell Publishing.

• Example : Employment Instability and Fertility in Europe: A Meta-Analysis:  10.1215/00703370-9164737

Meta-synthesis : "Qualitative meta-synthesis is a type of qualitative study that uses as data the findings from other qualitative studies linked by the same or related topic." (p.312). Zimmer, L. (2006). Qualitative meta-synthesis: A question of dialoguing with texts .  Journal of Advanced Nursing , 53 (3), 311-318.

• Example : Women’s perspectives on career successes and barriers: A qualitative meta-synthesis:  10.1177/05390184221113735

Literature Reviews in the Health Sciences

• UConn Health subject guide on systematic reviews Explanation of the different review types used in health sciences literature as well as tools to help you find the right review type
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What is a literature review?

A literature review is an integrated analysis -- not just a summary-- of scholarly writings and other relevant evidence related directly to your research question.  That is, it represents a synthesis of the evidence that provides background information on your topic and shows a association between the evidence and your research question.

A literature review may be a stand alone work or the introduction to a larger research paper, depending on the assignment.  Rely heavily on the guidelines your instructor has given you.

Why is it important?

A literature review is important because it:

• Explains the background of research on a topic.
• Demonstrates why a topic is significant to a subject area.
• Discovers relationships between research studies/ideas.
• Identifies major themes, concepts, and researchers on a topic.
• Identifies critical gaps and points of disagreement.
• Discusses further research questions that logically come out of the previous studies.

APA7 Style resources

APA Style Blog - for those harder to find answers

1. Choose a topic. Define your research question.

Your literature review should be guided by your central research question.  The literature represents background and research developments related to a specific research question, interpreted and analyzed by you in a synthesized way.

• Make sure your research question is not too broad or too narrow.  Is it manageable?
• Begin writing down terms that are related to your question. These will be useful for searches later.
• If you have the opportunity, discuss your topic with your professor and your class mates.

2. Decide on the scope of your review

How many studies do you need to look at? How comprehensive should it be? How many years should it cover? 

• This may depend on your assignment.  How many sources does the assignment require?

3. Select the databases you will use to conduct your searches.

Make a list of the databases you will search. 

Where to find databases:

• use the tabs on this guide
• Find other databases in the Nursing Information Resources web page
• More on the Medical Library web page
• ... and more on the Yale University Library web page

4. Conduct your searches to find the evidence. Keep track of your searches.

• Use the key words in your question, as well as synonyms for those words, as terms in your search. Use the database tutorials for help.
• Save the searches in the databases. This saves time when you want to redo, or modify, the searches. It is also helpful to use as a guide is the searches are not finding any useful results.
• Review the abstracts of research studies carefully. This will save you time.
• Use the bibliographies and references of research studies you find to locate others.
• Check with your professor, or a subject expert in the field, if you are missing any key works in the field.
• Ask your librarian for help at any time.
• Use a citation manager, such as EndNote as the repository for your citations. See the EndNote tutorials for help.

Review the literature

Some questions to help you analyze the research:

• What was the research question of the study you are reviewing? What were the authors trying to discover?
• Was the research funded by a source that could influence the findings?
• What were the research methodologies? Analyze its literature review, the samples and variables used, the results, and the conclusions.
• Does the research seem to be complete? Could it have been conducted more soundly? What further questions does it raise?
• If there are conflicting studies, why do you think that is?
• How are the authors viewed in the field? Has this study been cited? If so, how has it been analyzed?

Tips: 

• Review the abstracts carefully.  
• Keep careful notes so that you may track your thought processes during the research process.
• Create a matrix of the studies for easy analysis, and synthesis, across all of the studies.
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• 5. The Literature Review
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A literature review surveys prior research published in books, scholarly articles, and any other sources relevant to a particular issue, area of research, or theory, and by so doing, provides a description, summary, and critical evaluation of these works in relation to the research problem being investigated. Literature reviews are designed to provide an overview of sources you have used in researching a particular topic and to demonstrate to your readers how your research fits within existing scholarship about the topic.

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . Fourth edition. Thousand Oaks, CA: SAGE, 2014.

Importance of a Good Literature Review

A literature review may consist of simply a summary of key sources, but in the social sciences, a literature review usually has an organizational pattern and combines both summary and synthesis, often within specific conceptual categories . A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information in a way that informs how you are planning to investigate a research problem. The analytical features of a literature review might:

• Give a new interpretation of old material or combine new with old interpretations,
• Trace the intellectual progression of the field, including major debates,
• Depending on the situation, evaluate the sources and advise the reader on the most pertinent or relevant research, or
• Usually in the conclusion of a literature review, identify where gaps exist in how a problem has been researched to date.

Given this, the purpose of a literature review is to:

• Place each work in the context of its contribution to understanding the research problem being studied.
• Describe the relationship of each work to the others under consideration.
• Identify new ways to interpret prior research.
• Reveal any gaps that exist in the literature.
• Resolve conflicts amongst seemingly contradictory previous studies.
• Identify areas of prior scholarship to prevent duplication of effort.
• Point the way in fulfilling a need for additional research.
• Locate your own research within the context of existing literature [very important].

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper. 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . Los Angeles, CA: SAGE, 2011; Knopf, Jeffrey W. "Doing a Literature Review." PS: Political Science and Politics 39 (January 2006): 127-132; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012.

Types of Literature Reviews

It is important to think of knowledge in a given field as consisting of three layers. First, there are the primary studies that researchers conduct and publish. Second are the reviews of those studies that summarize and offer new interpretations built from and often extending beyond the primary studies. Third, there are the perceptions, conclusions, opinion, and interpretations that are shared informally among scholars that become part of the body of epistemological traditions within the field.

In composing a literature review, it is important to note that it is often this third layer of knowledge that is cited as "true" even though it often has only a loose relationship to the primary studies and secondary literature reviews. Given this, while literature reviews are designed to provide an overview and synthesis of pertinent sources you have explored, there are a number of approaches you could adopt depending upon the type of analysis underpinning your study.

Argumentative Review This form examines literature selectively in order to support or refute an argument, deeply embedded assumption, or philosophical problem already established in the literature. The purpose is to develop a body of literature that establishes a contrarian viewpoint. Given the value-laden nature of some social science research [e.g., educational reform; immigration control], argumentative approaches to analyzing the literature can be a legitimate and important form of discourse. However, note that they can also introduce problems of bias when they are used to make summary claims of the sort found in systematic reviews [see below].

Integrative Review Considered a form of research that reviews, critiques, and synthesizes representative literature on a topic in an integrated way such that new frameworks and perspectives on the topic are generated. The body of literature includes all studies that address related or identical hypotheses or research problems. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor, and replication. This is the most common form of review in the social sciences.

Historical Review Few things rest in isolation from historical precedent. Historical literature reviews focus on examining research throughout a period of time, often starting with the first time an issue, concept, theory, phenomena emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and to identify the likely directions for future research.

Methodological Review A review does not always focus on what someone said [findings], but how they came about saying what they say [method of analysis]. Reviewing methods of analysis provides a framework of understanding at different levels [i.e. those of theory, substantive fields, research approaches, and data collection and analysis techniques], how researchers draw upon a wide variety of knowledge ranging from the conceptual level to practical documents for use in fieldwork in the areas of ontological and epistemological consideration, quantitative and qualitative integration, sampling, interviewing, data collection, and data analysis. This approach helps highlight ethical issues which you should be aware of and consider as you go through your own study.

Systematic Review This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research, and to collect, report, and analyze data from the studies that are included in the review. The goal is to deliberately document, critically evaluate, and summarize scientifically all of the research about a clearly defined research problem . Typically it focuses on a very specific empirical question, often posed in a cause-and-effect form, such as "To what extent does A contribute to B?" This type of literature review is primarily applied to examining prior research studies in clinical medicine and allied health fields, but it is increasingly being used in the social sciences.

Theoretical Review The purpose of this form is to examine the corpus of theory that has accumulated in regard to an issue, concept, theory, phenomena. The theoretical literature review helps to establish what theories already exist, the relationships between them, to what degree the existing theories have been investigated, and to develop new hypotheses to be tested. Often this form is used to help establish a lack of appropriate theories or reveal that current theories are inadequate for explaining new or emerging research problems. The unit of analysis can focus on a theoretical concept or a whole theory or framework.

NOTE: Most often the literature review will incorporate some combination of types. For example, a review that examines literature supporting or refuting an argument, assumption, or philosophical problem related to the research problem will also need to include writing supported by sources that establish the history of these arguments in the literature.

Baumeister, Roy F. and Mark R. Leary. "Writing Narrative Literature Reviews."  Review of General Psychology 1 (September 1997): 311-320; Mark R. Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Kennedy, Mary M. "Defining a Literature." Educational Researcher 36 (April 2007): 139-147; Petticrew, Mark and Helen Roberts. Systematic Reviews in the Social Sciences: A Practical Guide . Malden, MA: Blackwell Publishers, 2006; Torracro, Richard. "Writing Integrative Literature Reviews: Guidelines and Examples." Human Resource Development Review 4 (September 2005): 356-367; Rocco, Tonette S. and Maria S. Plakhotnik. "Literature Reviews, Conceptual Frameworks, and Theoretical Frameworks: Terms, Functions, and Distinctions." Human Ressource Development Review 8 (March 2008): 120-130; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

Structure and Writing Style

I.  Thinking About Your Literature Review

The structure of a literature review should include the following in support of understanding the research problem :

• An overview of the subject, issue, or theory under consideration, along with the objectives of the literature review,
• Division of works under review into themes or categories [e.g. works that support a particular position, those against, and those offering alternative approaches entirely],
• An explanation of how each work is similar to and how it varies from the others,
• Conclusions as to which pieces are best considered in their argument, are most convincing of their opinions, and make the greatest contribution to the understanding and development of their area of research.

The critical evaluation of each work should consider :

• Provenance -- what are the author's credentials? Are the author's arguments supported by evidence [e.g. primary historical material, case studies, narratives, statistics, recent scientific findings]?
• Methodology -- were the techniques used to identify, gather, and analyze the data appropriate to addressing the research problem? Was the sample size appropriate? Were the results effectively interpreted and reported?
• Objectivity -- is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
• Persuasiveness -- which of the author's theses are most convincing or least convincing?
• Validity -- are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?

II.  Development of the Literature Review

Four Basic Stages of Writing 1.  Problem formulation -- which topic or field is being examined and what are its component issues? 2.  Literature search -- finding materials relevant to the subject being explored. 3.  Data evaluation -- determining which literature makes a significant contribution to the understanding of the topic. 4.  Analysis and interpretation -- discussing the findings and conclusions of pertinent literature.

Consider the following issues before writing the literature review: Clarify If your assignment is not specific about what form your literature review should take, seek clarification from your professor by asking these questions: 1.  Roughly how many sources would be appropriate to include? 2.  What types of sources should I review (books, journal articles, websites; scholarly versus popular sources)? 3.  Should I summarize, synthesize, or critique sources by discussing a common theme or issue? 4.  Should I evaluate the sources in any way beyond evaluating how they relate to understanding the research problem? 5.  Should I provide subheadings and other background information, such as definitions and/or a history? Find Models Use the exercise of reviewing the literature to examine how authors in your discipline or area of interest have composed their literature review sections. Read them to get a sense of the types of themes you might want to look for in your own research or to identify ways to organize your final review. The bibliography or reference section of sources you've already read, such as required readings in the course syllabus, are also excellent entry points into your own research. Narrow the Topic The narrower your topic, the easier it will be to limit the number of sources you need to read in order to obtain a good survey of relevant resources. Your professor will probably not expect you to read everything that's available about the topic, but you'll make the act of reviewing easier if you first limit scope of the research problem. A good strategy is to begin by searching the USC Libraries Catalog for recent books about the topic and review the table of contents for chapters that focuses on specific issues. You can also review the indexes of books to find references to specific issues that can serve as the focus of your research. For example, a book surveying the history of the Israeli-Palestinian conflict may include a chapter on the role Egypt has played in mediating the conflict, or look in the index for the pages where Egypt is mentioned in the text. Consider Whether Your Sources are Current Some disciplines require that you use information that is as current as possible. This is particularly true in disciplines in medicine and the sciences where research conducted becomes obsolete very quickly as new discoveries are made. However, when writing a review in the social sciences, a survey of the history of the literature may be required. In other words, a complete understanding the research problem requires you to deliberately examine how knowledge and perspectives have changed over time. Sort through other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to explore what is considered by scholars to be a "hot topic" and what is not.

III.  Ways to Organize Your Literature Review

Chronology of Events If your review follows the chronological method, you could write about the materials according to when they were published. This approach should only be followed if a clear path of research building on previous research can be identified and that these trends follow a clear chronological order of development. For example, a literature review that focuses on continuing research about the emergence of German economic power after the fall of the Soviet Union. By Publication Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on environmental studies of brown fields if the progression revealed, for example, a change in the soil collection practices of the researchers who wrote and/or conducted the studies. Thematic [“conceptual categories”] A thematic literature review is the most common approach to summarizing prior research in the social and behavioral sciences. Thematic reviews are organized around a topic or issue, rather than the progression of time, although the progression of time may still be incorporated into a thematic review. For example, a review of the Internet’s impact on American presidential politics could focus on the development of online political satire. While the study focuses on one topic, the Internet’s impact on American presidential politics, it would still be organized chronologically reflecting technological developments in media. The difference in this example between a "chronological" and a "thematic" approach is what is emphasized the most: themes related to the role of the Internet in presidential politics. Note that more authentic thematic reviews tend to break away from chronological order. A review organized in this manner would shift between time periods within each section according to the point being made. Methodological A methodological approach focuses on the methods utilized by the researcher. For the Internet in American presidential politics project, one methodological approach would be to look at cultural differences between the portrayal of American presidents on American, British, and French websites. Or the review might focus on the fundraising impact of the Internet on a particular political party. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed.

Other Sections of Your Literature Review Once you've decided on the organizational method for your literature review, the sections you need to include in the paper should be easy to figure out because they arise from your organizational strategy. In other words, a chronological review would have subsections for each vital time period; a thematic review would have subtopics based upon factors that relate to the theme or issue. However, sometimes you may need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. However, only include what is necessary for the reader to locate your study within the larger scholarship about the research problem.

Here are examples of other sections, usually in the form of a single paragraph, you may need to include depending on the type of review you write:

• Current Situation : Information necessary to understand the current topic or focus of the literature review.
• Sources Used : Describes the methods and resources [e.g., databases] you used to identify the literature you reviewed.
• History : The chronological progression of the field, the research literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Selection Methods : Criteria you used to select (and perhaps exclude) sources in your literature review. For instance, you might explain that your review includes only peer-reviewed [i.e., scholarly] sources.
• Standards : Description of the way in which you present your information.
• Questions for Further Research : What questions about the field has the review sparked? How will you further your research as a result of the review?

IV.  Writing Your Literature Review

Once you've settled on how to organize your literature review, you're ready to write each section. When writing your review, keep in mind these issues.

Use Evidence A literature review section is, in this sense, just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence [citations] that demonstrates that what you are saying is valid. Be Selective Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the research problem, whether it is thematic, methodological, or chronological. Related items that provide additional information, but that are not key to understanding the research problem, can be included in a list of further readings . Use Quotes Sparingly Some short quotes are appropriate if you want to emphasize a point, or if what an author stated cannot be easily paraphrased. Sometimes you may need to quote certain terminology that was coined by the author, is not common knowledge, or taken directly from the study. Do not use extensive quotes as a substitute for using your own words in reviewing the literature. Summarize and Synthesize Remember to summarize and synthesize your sources within each thematic paragraph as well as throughout the review. Recapitulate important features of a research study, but then synthesize it by rephrasing the study's significance and relating it to your own work and the work of others. Keep Your Own Voice While the literature review presents others' ideas, your voice [the writer's] should remain front and center. For example, weave references to other sources into what you are writing but maintain your own voice by starting and ending the paragraph with your own ideas and wording. Use Caution When Paraphrasing When paraphrasing a source that is not your own, be sure to represent the author's information or opinions accurately and in your own words. Even when paraphrasing an author’s work, you still must provide a citation to that work.

V.  Common Mistakes to Avoid

These are the most common mistakes made in reviewing social science research literature.

• Sources in your literature review do not clearly relate to the research problem;
• You do not take sufficient time to define and identify the most relevant sources to use in the literature review related to the research problem;
• Relies exclusively on secondary analytical sources rather than including relevant primary research studies or data;
• Uncritically accepts another researcher's findings and interpretations as valid, rather than examining critically all aspects of the research design and analysis;
• Does not describe the search procedures that were used in identifying the literature to review;
• Reports isolated statistical results rather than synthesizing them in chi-squared or meta-analytic methods; and,
• Only includes research that validates assumptions and does not consider contrary findings and alternative interpretations found in the literature.

Cook, Kathleen E. and Elise Murowchick. “Do Literature Review Skills Transfer from One Course to Another?” Psychology Learning and Teaching 13 (March 2014): 3-11; Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . London: SAGE, 2011; Literature Review Handout. Online Writing Center. Liberty University; Literature Reviews. The Writing Center. University of North Carolina; Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: SAGE, 2016; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012; Randolph, Justus J. “A Guide to Writing the Dissertation Literature Review." Practical Assessment, Research, and Evaluation. vol. 14, June 2009; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016; Taylor, Dena. The Literature Review: A Few Tips On Conducting It. University College Writing Centre. University of Toronto; Writing a Literature Review. Academic Skills Centre. University of Canberra.

Writing Tip

Break Out of Your Disciplinary Box!

Thinking interdisciplinarily about a research problem can be a rewarding exercise in applying new ideas, theories, or concepts to an old problem. For example, what might cultural anthropologists say about the continuing conflict in the Middle East? In what ways might geographers view the need for better distribution of social service agencies in large cities than how social workers might study the issue? You don’t want to substitute a thorough review of core research literature in your discipline for studies conducted in other fields of study. However, particularly in the social sciences, thinking about research problems from multiple vectors is a key strategy for finding new solutions to a problem or gaining a new perspective. Consult with a librarian about identifying research databases in other disciplines; almost every field of study has at least one comprehensive database devoted to indexing its research literature.

Frodeman, Robert. The Oxford Handbook of Interdisciplinarity . New York: Oxford University Press, 2010.

Another Writing Tip

Don't Just Review for Content!

While conducting a review of the literature, maximize the time you devote to writing this part of your paper by thinking broadly about what you should be looking for and evaluating. Review not just what scholars are saying, but how are they saying it. Some questions to ask:

• How are they organizing their ideas?
• What methods have they used to study the problem?
• What theories have been used to explain, predict, or understand their research problem?
• What sources have they cited to support their conclusions?
• How have they used non-textual elements [e.g., charts, graphs, figures, etc.] to illustrate key points?

When you begin to write your literature review section, you'll be glad you dug deeper into how the research was designed and constructed because it establishes a means for developing more substantial analysis and interpretation of the research problem.

Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1 998.

Yet Another Writing Tip

When Do I Know I Can Stop Looking and Move On?

Here are several strategies you can utilize to assess whether you've thoroughly reviewed the literature:

• Look for repeating patterns in the research findings . If the same thing is being said, just by different people, then this likely demonstrates that the research problem has hit a conceptual dead end. At this point consider: Does your study extend current research?  Does it forge a new path? Or, does is merely add more of the same thing being said?
• Look at sources the authors cite to in their work . If you begin to see the same researchers cited again and again, then this is often an indication that no new ideas have been generated to address the research problem.
• Search Google Scholar to identify who has subsequently cited leading scholars already identified in your literature review [see next sub-tab]. This is called citation tracking and there are a number of sources that can help you identify who has cited whom, particularly scholars from outside of your discipline. Here again, if the same authors are being cited again and again, this may indicate no new literature has been written on the topic.

Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: Sage, 2016; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

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Literature Reviews

• What is a literature review?
• Steps in the Literature Review Process
• Define your research question
• Determine inclusion and exclusion criteria
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• Review Results
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What is a Literature Review?

A literature or narrative review is a comprehensive review and analysis of the published literature on a specific topic or research question. The literature that is reviewed contains: books, articles, academic articles, conference proceedings, association papers, and dissertations. It contains the most pertinent studies and points to important past and current research and practices. It provides background and context, and shows how your research will contribute to the field. 

A literature review should: 

• Provide a comprehensive and updated review of the literature;
• Explain why this review has taken place;
• Articulate a position or hypothesis;
• Acknowledge and account for conflicting and corroborating points of view

From  S age Research Methods

Purpose of a Literature Review

A literature review can be written as an introduction to a study to:

• Demonstrate how a study fills a gap in research
• Compare a study with other research that's been done

Or it can be a separate work (a research article on its own) which:

• Organizes or describes a topic
• Describes variables within a particular issue/problem

Limitations of a Literature Review

Some of the limitations of a literature review are:

• It's a snapshot in time. Unlike other reviews, this one has beginning, a middle and an end. There may be future developments that could make your work less relevant.
• It may be too focused. Some niche studies may miss the bigger picture.
• It can be difficult to be comprehensive. There is no way to make sure all the literature on a topic was considered.
• It is easy to be biased if you stick to top tier journals. There may be other places where people are publishing exemplary research. Look to open access publications and conferences to reflect a more inclusive collection. Also, make sure to include opposing views (and not just supporting evidence).

Source: Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal, vol. 26, no. 2, June 2009, pp. 91–108. Wiley Online Library, doi:10.1111/j.1471-1842.2009.00848.x.

Meryl Brodsky : Communication and Information Studies

Hannah Chapman Tripp : Biology, Neuroscience

Carolyn Cunningham : Human Development & Family Sciences, Psychology, Sociology

Larayne Dallas : Engineering

Janelle Hedstrom : Special Education, Curriculum & Instruction, Ed Leadership & Policy ​

Susan Macicak : Linguistics

Imelda Vetter : Dell Medical School

For help in other subject areas, please see the guide to library specialists by subject .

Periodically, UT Libraries runs a workshop covering the basics and library support for literature reviews. While we try to offer these once per academic year, we find providing the recording to be helpful to community members who have missed the session. Following is the most recent recording of the workshop, Conducting a Literature Review. To view the recording, a UT login is required.

• October 26, 2022 recording
• Last Updated: Oct 26, 2022 2:49 PM
• URL: https://guides.lib.utexas.edu/literaturereviews

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• What is a Literature Review? | Guide, Template, & Examples

What is a Literature Review? | Guide, Template, & Examples

Published on 22 February 2022 by Shona McCombes . Revised on 7 June 2022.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research.

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarise sources – it analyses, synthesises, and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

Why write a literature review, examples of literature reviews, step 1: search for relevant literature, step 2: evaluate and select sources, step 3: identify themes, debates and gaps, step 4: outline your literature review’s structure, step 5: write your literature review, frequently asked questions about literature reviews, introduction.

• Quick Run-through
• Step 1 & 2

When you write a dissertation or thesis, you will have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and scholarly context
• Develop a theoretical framework and methodology for your research
• Position yourself in relation to other researchers and theorists
• Show how your dissertation addresses a gap or contributes to a debate

You might also have to write a literature review as a stand-alone assignment. In this case, the purpose is to evaluate the current state of research and demonstrate your knowledge of scholarly debates around a topic.

The content will look slightly different in each case, but the process of conducting a literature review follows the same steps. We’ve written a step-by-step guide that you can follow below.

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Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research objectives and questions .

If you are writing a literature review as a stand-alone assignment, you will have to choose a focus and develop a central question to direct your search. Unlike a dissertation research question, this question has to be answerable without collecting original data. You should be able to answer it based only on a review of existing publications.

Make a list of keywords

Start by creating a list of keywords related to your research topic. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list if you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can use boolean operators to help narrow down your search:

Read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

To identify the most important publications on your topic, take note of recurring citations. If the same authors, books or articles keep appearing in your reading, make sure to seek them out.

You probably won’t be able to read absolutely everything that has been written on the topic – you’ll have to evaluate which sources are most relevant to your questions.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models and methods? Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• How does the publication contribute to your understanding of the topic? What are its key insights and arguments?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible, and make sure you read any landmark studies and major theories in your field of research.

You can find out how many times an article has been cited on Google Scholar – a high citation count means the article has been influential in the field, and should certainly be included in your literature review.

The scope of your review will depend on your topic and discipline: in the sciences you usually only review recent literature, but in the humanities you might take a long historical perspective (for example, to trace how a concept has changed in meaning over time).

Remember that you can use our template to summarise and evaluate sources you’re thinking about using!

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It’s important to keep track of your sources with references to avoid plagiarism . It can be helpful to make an annotated bibliography, where you compile full reference information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

You can use our free APA Reference Generator for quick, correct, consistent citations.

To begin organising your literature review’s argument and structure, you need to understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly-visual platforms like Instagram and Snapchat – this is a gap that you could address in your own research.

There are various approaches to organising the body of a literature review. You should have a rough idea of your strategy before you start writing.

Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarising sources in order.

Try to analyse patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organise your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text, your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

If you are writing the literature review as part of your dissertation or thesis, reiterate your central problem or research question and give a brief summary of the scholarly context. You can emphasise the timeliness of the topic (“many recent studies have focused on the problem of x”) or highlight a gap in the literature (“while there has been much research on x, few researchers have taken y into consideration”).

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, make sure to follow these tips:

• Summarise and synthesise: give an overview of the main points of each source and combine them into a coherent whole.
• Analyse and interpret: don’t just paraphrase other researchers – add your own interpretations, discussing the significance of findings in relation to the literature as a whole.
• Critically evaluate: mention the strengths and weaknesses of your sources.
• Write in well-structured paragraphs: use transitions and topic sentences to draw connections, comparisons and contrasts.

In the conclusion, you should summarise the key findings you have taken from the literature and emphasise their significance.

If the literature review is part of your dissertation or thesis, reiterate how your research addresses gaps and contributes new knowledge, or discuss how you have drawn on existing theories and methods to build a framework for your research. This can lead directly into your methodology section.

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a dissertation , thesis, research paper , or proposal .

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarise yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your  dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

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Learn how to write a review of literature

What is a review of literature.

The format of a review of literature may vary from discipline to discipline and from assignment to assignment.

A review may be a self-contained unit — an end in itself — or a preface to and rationale for engaging in primary research. A review is a required part of grant and research proposals and often a chapter in theses and dissertations.

Generally, the purpose of a review is to analyze critically a segment of a published body of knowledge through summary, classification, and comparison of prior research studies, reviews of literature, and theoretical articles.

Writing the introduction

In the introduction, you should:

Define or identify the general topic, issue, or area of concern, thus providing an appropriate context for reviewing the literature.

Point out overall trends in what has been published about the topic; or conflicts in theory, methodology, evidence, and conclusions; or gaps in research and scholarship; or a single problem or new perspective of immediate interest.

Establish the writer’s reason (point of view) for reviewing the literature; explain the criteria to be used in analyzing and comparing literature and the organization of the review (sequence); and, when necessary, state why certain literature is or is not included (scope).

Writing the body

In the body, you should:

Group research studies and other types of literature (reviews, theoretical articles, case studies, etc.) according to common denominators such as qualitative versus quantitative approaches, conclusions of authors, specific purpose or objective, chronology, etc.

Summarize individual studies or articles with as much or as little detail as each merits according to its comparative importance in the literature, remembering that space (length) denotes significance.

Provide the reader with strong “umbrella” sentences at beginnings of paragraphs, “signposts” throughout, and brief “so what” summary sentences at intermediate points in the review to aid in understanding comparisons and analyses.

Writing the conclusion

In the conclusion, you should:

Summarize major contributions of significant studies and articles to the body of knowledge under review, maintaining the focus established in the introduction.

Evaluate the current “state of the art” for the body of knowledge reviewed, pointing out major methodological flaws or gaps in research, inconsistencies in theory and findings, and areas or issues pertinent to future study.

Conclude by providing some insight into the relationship between the central topic of the literature review and a larger area of study such as a discipline, a scientific endeavor, or a profession.

For further information see our handouts on Writing a Critical Review of a Nonfiction Book or Article or Reading a Book to Review It .

To learn more about literature reviews, take a look at our workshop on Writing Literature Reviews of Published Research.

Sample Literature Reviews

An important strategy for learning how to compose literature reviews in your field or within a specific genre is to locate and analyze representative examples. The following collection of annotated sample literature reviews written and co-written by colleagues associated with UW-Madison showcases how these reviews can do different kind of work for different purposes. Use these successful examples as a starting point for understanding how other writers have approached the challenging and important task of situating their idea in the context of established research.

• Sample 1 (PDF) A brief literature review within a political scientists’  National Science Foundation Graduate Research Fellowship  grant
• Sample 2 (PDF) A several-page literature review at the beginning of a published, academic article about philosophy
• Sample 3 (PDF) A brief literature review at the beginning of a published, academic article about photochemistry

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Research Process :: Step by Step

• Introduction
• Select Topic
• Identify Keywords
• Background Information
• Develop Research Questions
• Refine Topic
• Search Strategy
• Popular Databases
• Evaluate Sources
• Types of Periodicals
• Reading Scholarly Articles
• Primary & Secondary Sources
• Organize / Take Notes
• Writing & Grammar Resources
• Annotated Bibliography
• Literature Review
• Citation Styles
• Paraphrasing
• Privacy / Confidentiality
• Research Process
• Selecting Your Topic
• Identifying Keywords
• Gathering Background Info
• Evaluating Sources

Organize the literature review into sections that present themes or identify trends, including relevant theory. You are not trying to list all the material published, but to synthesize and evaluate it according to the guiding concept of your thesis or research question.  

What is a literature review?

A literature review is an account of what has been published on a topic by accredited scholars and researchers. Occasionally you will be asked to write one as a separate assignment, but more often it is part of the introduction to an essay, research report, or thesis. In writing the literature review, your purpose is to convey to your reader what knowledge and ideas have been established on a topic, and what their strengths and weaknesses are. As a piece of writing, the literature review must be defined by a guiding concept (e.g., your research objective, the problem or issue you are discussing, or your argumentative thesis). It is not just a descriptive list of the material available, or a set of summaries

A literature review must do these things:

• be organized around and related directly to the thesis or research question you are developing
• synthesize results into a summary of what is and is not known
• identify areas of controversy in the literature
• formulate questions that need further research

Ask yourself questions like these:

• What is the specific thesis, problem, or research question that my literature review helps to define?
• What type of literature review am I conducting? Am I looking at issues of theory? methodology? policy? quantitative research (e.g. on the effectiveness of a new procedure)? qualitative research (e.g., studies of loneliness among migrant workers)?
• What is the scope of my literature review? What types of publications am I using (e.g., journals, books, government documents, popular media)? What discipline am I working in (e.g., nursing psychology, sociology, medicine)?
• How good was my information seeking? Has my search been wide enough to ensure I've found all the relevant material? Has it been narrow enough to exclude irrelevant material? Is the number of sources I've used appropriate for the length of my paper?
• Have I critically analyzed the literature I use? Do I follow through a set of concepts and questions, comparing items to each other in the ways they deal with them? Instead of just listing and summarizing items, do I assess them, discussing strengths and weaknesses?
• Have I cited and discussed studies contrary to my perspective?
• Will the reader find my literature review relevant, appropriate, and useful?

Ask yourself questions like these about each book or article you include:

• Has the author formulated a problem/issue?
• Is it clearly defined? Is its significance (scope, severity, relevance) clearly established?
• Could the problem have been approached more effectively from another perspective?
• What is the author's research orientation (e.g., interpretive, critical science, combination)?
• What is the author's theoretical framework (e.g., psychological, developmental, feminist)?
• What is the relationship between the theoretical and research perspectives?
• Has the author evaluated the literature relevant to the problem/issue? Does the author include literature taking positions she or he does not agree with?
• In a research study, how good are the basic components of the study design (e.g., population, intervention, outcome)? How accurate and valid are the measurements? Is the analysis of the data accurate and relevant to the research question? Are the conclusions validly based upon the data and analysis?
• In material written for a popular readership, does the author use appeals to emotion, one-sided examples, or rhetorically-charged language and tone? Is there an objective basis to the reasoning, or is the author merely "proving" what he or she already believes?
• How does the author structure the argument? Can you "deconstruct" the flow of the argument to see whether or where it breaks down logically (e.g., in establishing cause-effect relationships)?
• In what ways does this book or article contribute to our understanding of the problem under study, and in what ways is it useful for practice? What are the strengths and limitations?
• How does this book or article relate to the specific thesis or question I am developing?

Text written by Dena Taylor, Health Sciences Writing Centre, University of Toronto

http://www.writing.utoronto.ca/advice/specific-types-of-writing/literature-review

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What is a Literature Review? How to Write It (with Examples)

A literature review is a critical analysis and synthesis of existing research on a particular topic. It provides an overview of the current state of knowledge, identifies gaps, and highlights key findings in the literature. 1 The purpose of a literature review is to situate your own research within the context of existing scholarship, demonstrating your understanding of the topic and showing how your work contributes to the ongoing conversation in the field. Learning how to write a literature review is a critical tool for successful research. Your ability to summarize and synthesize prior research pertaining to a certain topic demonstrates your grasp on the topic of study, and assists in the learning process. 

Table of Contents

• What is the purpose of literature review? 
• a. Habitat Loss and Species Extinction: 
• b. Range Shifts and Phenological Changes: 
• c. Ocean Acidification and Coral Reefs: 
• d. Adaptive Strategies and Conservation Efforts: 

How to write a good literature review 

• Choose a Topic and Define the Research Question: 
• Decide on the Scope of Your Review: 
• Select Databases for Searches: 
• Conduct Searches and Keep Track: 
• Review the Literature: 
• Organize and Write Your Literature Review: 
• How to write a literature review faster with Paperpal? 
• Frequently asked questions 

What is a literature review?

A well-conducted literature review demonstrates the researcher’s familiarity with the existing literature, establishes the context for their own research, and contributes to scholarly conversations on the topic. One of the purposes of a literature review is also to help researchers avoid duplicating previous work and ensure that their research is informed by and builds upon the existing body of knowledge.

What is the purpose of literature review?

A literature review serves several important purposes within academic and research contexts. Here are some key objectives and functions of a literature review: 2  

1. Contextualizing the Research Problem: The literature review provides a background and context for the research problem under investigation. It helps to situate the study within the existing body of knowledge. 

2. Identifying Gaps in Knowledge: By identifying gaps, contradictions, or areas requiring further research, the researcher can shape the research question and justify the significance of the study. This is crucial for ensuring that the new research contributes something novel to the field. 

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3. Understanding Theoretical and Conceptual Frameworks: Literature reviews help researchers gain an understanding of the theoretical and conceptual frameworks used in previous studies. This aids in the development of a theoretical framework for the current research. 

4. Providing Methodological Insights: Another purpose of literature reviews is that it allows researchers to learn about the methodologies employed in previous studies. This can help in choosing appropriate research methods for the current study and avoiding pitfalls that others may have encountered. 

5. Establishing Credibility: A well-conducted literature review demonstrates the researcher’s familiarity with existing scholarship, establishing their credibility and expertise in the field. It also helps in building a solid foundation for the new research. 

6. Informing Hypotheses or Research Questions: The literature review guides the formulation of hypotheses or research questions by highlighting relevant findings and areas of uncertainty in existing literature. 

Literature review example

Let’s delve deeper with a literature review example: Let’s say your literature review is about the impact of climate change on biodiversity. You might format your literature review into sections such as the effects of climate change on habitat loss and species extinction, phenological changes, and marine biodiversity. Each section would then summarize and analyze relevant studies in those areas, highlighting key findings and identifying gaps in the research. The review would conclude by emphasizing the need for further research on specific aspects of the relationship between climate change and biodiversity. The following literature review template provides a glimpse into the recommended literature review structure and content, demonstrating how research findings are organized around specific themes within a broader topic. 

Literature Review on Climate Change Impacts on Biodiversity:

Climate change is a global phenomenon with far-reaching consequences, including significant impacts on biodiversity. This literature review synthesizes key findings from various studies: 

a. Habitat Loss and Species Extinction:

Climate change-induced alterations in temperature and precipitation patterns contribute to habitat loss, affecting numerous species (Thomas et al., 2004). The review discusses how these changes increase the risk of extinction, particularly for species with specific habitat requirements. 

b. Range Shifts and Phenological Changes:

Observations of range shifts and changes in the timing of biological events (phenology) are documented in response to changing climatic conditions (Parmesan & Yohe, 2003). These shifts affect ecosystems and may lead to mismatches between species and their resources. 

c. Ocean Acidification and Coral Reefs:

The review explores the impact of climate change on marine biodiversity, emphasizing ocean acidification’s threat to coral reefs (Hoegh-Guldberg et al., 2007). Changes in pH levels negatively affect coral calcification, disrupting the delicate balance of marine ecosystems. 

d. Adaptive Strategies and Conservation Efforts:

Recognizing the urgency of the situation, the literature review discusses various adaptive strategies adopted by species and conservation efforts aimed at mitigating the impacts of climate change on biodiversity (Hannah et al., 2007). It emphasizes the importance of interdisciplinary approaches for effective conservation planning. 

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Writing a literature review involves summarizing and synthesizing existing research on a particular topic. A good literature review format should include the following elements. 

Introduction: The introduction sets the stage for your literature review, providing context and introducing the main focus of your review. 

• Opening Statement: Begin with a general statement about the broader topic and its significance in the field. 
• Scope and Purpose: Clearly define the scope of your literature review. Explain the specific research question or objective you aim to address. 
• Organizational Framework: Briefly outline the structure of your literature review, indicating how you will categorize and discuss the existing research. 
• Significance of the Study: Highlight why your literature review is important and how it contributes to the understanding of the chosen topic. 
• Thesis Statement: Conclude the introduction with a concise thesis statement that outlines the main argument or perspective you will develop in the body of the literature review. 

Body: The body of the literature review is where you provide a comprehensive analysis of existing literature, grouping studies based on themes, methodologies, or other relevant criteria. 

• Organize by Theme or Concept: Group studies that share common themes, concepts, or methodologies. Discuss each theme or concept in detail, summarizing key findings and identifying gaps or areas of disagreement. 
• Critical Analysis: Evaluate the strengths and weaknesses of each study. Discuss the methodologies used, the quality of evidence, and the overall contribution of each work to the understanding of the topic. 
• Synthesis of Findings: Synthesize the information from different studies to highlight trends, patterns, or areas of consensus in the literature. 
• Identification of Gaps: Discuss any gaps or limitations in the existing research and explain how your review contributes to filling these gaps. 
• Transition between Sections: Provide smooth transitions between different themes or concepts to maintain the flow of your literature review. 

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Conclusion: The conclusion of your literature review should summarize the main findings, highlight the contributions of the review, and suggest avenues for future research. 

• Summary of Key Findings: Recap the main findings from the literature and restate how they contribute to your research question or objective. 
• Contributions to the Field: Discuss the overall contribution of your literature review to the existing knowledge in the field. 
• Implications and Applications: Explore the practical implications of the findings and suggest how they might impact future research or practice. 
• Recommendations for Future Research: Identify areas that require further investigation and propose potential directions for future research in the field. 
• Final Thoughts: Conclude with a final reflection on the importance of your literature review and its relevance to the broader academic community. 

Conducting a literature review

Conducting a literature review is an essential step in research that involves reviewing and analyzing existing literature on a specific topic. It’s important to know how to do a literature review effectively, so here are the steps to follow: 1  

Choose a Topic and Define the Research Question:

• Select a topic that is relevant to your field of study. 
• Clearly define your research question or objective. Determine what specific aspect of the topic do you want to explore? 

Decide on the Scope of Your Review:

• Determine the timeframe for your literature review. Are you focusing on recent developments, or do you want a historical overview? 
• Consider the geographical scope. Is your review global, or are you focusing on a specific region? 
• Define the inclusion and exclusion criteria. What types of sources will you include? Are there specific types of studies or publications you will exclude? 

Select Databases for Searches:

• Identify relevant databases for your field. Examples include PubMed, IEEE Xplore, Scopus, Web of Science, and Google Scholar. 
• Consider searching in library catalogs, institutional repositories, and specialized databases related to your topic. 

Conduct Searches and Keep Track:

• Develop a systematic search strategy using keywords, Boolean operators (AND, OR, NOT), and other search techniques. 
• Record and document your search strategy for transparency and replicability. 
• Keep track of the articles, including publication details, abstracts, and links. Use citation management tools like EndNote, Zotero, or Mendeley to organize your references. 

Review the Literature:

• Evaluate the relevance and quality of each source. Consider the methodology, sample size, and results of studies. 
• Organize the literature by themes or key concepts. Identify patterns, trends, and gaps in the existing research. 
• Summarize key findings and arguments from each source. Compare and contrast different perspectives. 
• Identify areas where there is a consensus in the literature and where there are conflicting opinions. 
• Provide critical analysis and synthesis of the literature. What are the strengths and weaknesses of existing research? 

Organize and Write Your Literature Review:

• Literature review outline should be based on themes, chronological order, or methodological approaches. 
• Write a clear and coherent narrative that synthesizes the information gathered. 
• Use proper citations for each source and ensure consistency in your citation style (APA, MLA, Chicago, etc.). 
• Conclude your literature review by summarizing key findings, identifying gaps, and suggesting areas for future research. 

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The literature review sample and detailed advice on writing and conducting a review will help you produce a well-structured report. But remember that a good literature review is an ongoing process, and it may be necessary to revisit and update it as your research progresses. By combining effortless research with an easy citation process, Paperpal Research streamlines the literature review process and empowers you to write faster and with more confidence. Try Paperpal Research now and see for yourself.  

Frequently asked questions

A literature review is a critical and comprehensive analysis of existing literature (published and unpublished works) on a specific topic or research question and provides a synthesis of the current state of knowledge in a particular field. A well-conducted literature review is crucial for researchers to build upon existing knowledge, avoid duplication of efforts, and contribute to the advancement of their field. It also helps researchers situate their work within a broader context and facilitates the development of a sound theoretical and conceptual framework for their studies.

Literature review is a crucial component of research writing, providing a solid background for a research paper’s investigation. The aim is to keep professionals up to date by providing an understanding of ongoing developments within a specific field, including research methods, and experimental techniques used in that field, and present that knowledge in the form of a written report. Also, the depth and breadth of the literature review emphasizes the credibility of the scholar in his or her field.  

Before writing a literature review, it’s essential to undertake several preparatory steps to ensure that your review is well-researched, organized, and focused. This includes choosing a topic of general interest to you and doing exploratory research on that topic, writing an annotated bibliography, and noting major points, especially those that relate to the position you have taken on the topic. 

Literature reviews and academic research papers are essential components of scholarly work but serve different purposes within the academic realm. 3 A literature review aims to provide a foundation for understanding the current state of research on a particular topic, identify gaps or controversies, and lay the groundwork for future research. Therefore, it draws heavily from existing academic sources, including books, journal articles, and other scholarly publications. In contrast, an academic research paper aims to present new knowledge, contribute to the academic discourse, and advance the understanding of a specific research question. Therefore, it involves a mix of existing literature (in the introduction and literature review sections) and original data or findings obtained through research methods. 

Literature reviews are essential components of academic and research papers, and various strategies can be employed to conduct them effectively. If you want to know how to write a literature review for a research paper, here are four common approaches that are often used by researchers.  Chronological Review: This strategy involves organizing the literature based on the chronological order of publication. It helps to trace the development of a topic over time, showing how ideas, theories, and research have evolved.  Thematic Review: Thematic reviews focus on identifying and analyzing themes or topics that cut across different studies. Instead of organizing the literature chronologically, it is grouped by key themes or concepts, allowing for a comprehensive exploration of various aspects of the topic.  Methodological Review: This strategy involves organizing the literature based on the research methods employed in different studies. It helps to highlight the strengths and weaknesses of various methodologies and allows the reader to evaluate the reliability and validity of the research findings.  Theoretical Review: A theoretical review examines the literature based on the theoretical frameworks used in different studies. This approach helps to identify the key theories that have been applied to the topic and assess their contributions to the understanding of the subject.  It’s important to note that these strategies are not mutually exclusive, and a literature review may combine elements of more than one approach. The choice of strategy depends on the research question, the nature of the literature available, and the goals of the review. Additionally, other strategies, such as integrative reviews or systematic reviews, may be employed depending on the specific requirements of the research.

The literature review format can vary depending on the specific publication guidelines. However, there are some common elements and structures that are often followed. Here is a general guideline for the format of a literature review:  Introduction:   Provide an overview of the topic.  Define the scope and purpose of the literature review.  State the research question or objective.  Body:   Organize the literature by themes, concepts, or chronology.  Critically analyze and evaluate each source.  Discuss the strengths and weaknesses of the studies.  Highlight any methodological limitations or biases.  Identify patterns, connections, or contradictions in the existing research.  Conclusion:   Summarize the key points discussed in the literature review.  Highlight the research gap.  Address the research question or objective stated in the introduction.  Highlight the contributions of the review and suggest directions for future research.

Both annotated bibliographies and literature reviews involve the examination of scholarly sources. While annotated bibliographies focus on individual sources with brief annotations, literature reviews provide a more in-depth, integrated, and comprehensive analysis of existing literature on a specific topic. The key differences are as follows: 

References 

• Denney, A. S., & Tewksbury, R. (2013). How to write a literature review.  Journal of criminal justice education ,  24 (2), 218-234. 
• Pan, M. L. (2016).  Preparing literature reviews: Qualitative and quantitative approaches . Taylor & Francis. 
• Cantero, C. (2019). How to write a literature review.  San José State University Writing Center . 

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Chapter 9. Reviewing the Literature

What is a “literature review”.

No researcher ever comes up with a research question that is wholly novel. Someone, somewhere, has asked the same thing. Academic research is part of a larger community of researchers, and it is your responsibility, as a member of this community, to acknowledge others who have asked similar questions and to put your particular research into this greater context. It is not simply a convention or custom to begin your study with a review of previous literature (the “ lit review ”) but an important responsibility you owe the scholarly community.

Too often, new researchers pursue a topic to study and then write something like, “No one has ever studied this before” or “This area is underresearched.” It may be that no one has studied this particular group or setting, but it is highly unlikely no one has studied the foundational phenomenon of interest. And that comment about an area being underresearched? Be careful. The statement may simply signal to others that you haven’t done your homework. Rubin ( 2021 ) refers to this as “free soloing,” and it is not appreciated in academic work:

The truth of the matter is, academics don’t really like when people free solo. It’s really bad form to omit talking about the other people who are doing or have done research in your area. Partly, I mean we need to cite their work, but I also mean we need to respond to it—agree or disagree, clarify for extend. It’s also really bad form to talk about your research in a way that does not make it understandable to other academics.…You have to explain to your readers what your story is really about in terms they care about . This means using certain terminology, referencing debates in the literature, and citing relevant works—that is, in connecting your work to something else. ( 51–52 )

A literature review is a comprehensive summary of previous research on a topic. It includes both articles and books—and in some cases reports—relevant to a particular area of research. Ideally, one’s research question follows from the reading of what has already been produced. For example, you are interested in studying sports injuries related to female gymnasts. You read everything you can find on sports injuries related to female gymnasts, and you begin to get a sense of what questions remain open. You find that there is a lot of research on how coaches manage sports injuries and much about cultures of silence around treating injuries, but you don’t know what the gymnasts themselves are thinking about these issues. You look specifically for studies about this and find several, which then pushes you to narrow the question further. Your literature review then provides the road map of how you came to your very specific question, and it puts your study in the context of studies of sports injuries. What you eventually find can “speak to” all the related questions as well as your particular one.

In practice, the process is often a bit messier. Many researchers, and not simply those starting out, begin with a particular question and have a clear idea of who they want to study and where they want to conduct their study but don’t really know much about other studies at all. Although backward, we need to recognize this is pretty common. Telling students to “find literature” after the fact can seem like a purposeless task or just another hurdle for completing a thesis or dissertation. It is not! Even if you were not motivated by the literature in the first place, acknowledging similar studies and connecting your own research to those studies are important parts of building knowledge. Acknowledgment of past research is a responsibility you owe the discipline to which you belong.

Literature reviews can also signal theoretical approaches and particular concepts that you will incorporate into your own study. For example, let us say you are doing a study of how people find their first jobs after college, and you want to use the concept of social capital . There are competing definitions of social capital out there (e.g., Bourdieu vs. Burt vs. Putnam). Bourdieu’s notion is of one form of capital, or durable asset, of a “network of more or less institutionalized relationships of mutual acquaintance or recognition” ( 1984:248 ). Burt emphasizes the “brokerage opportunities” in a social network as social capital ( 1997:355 ). Putnam’s social capital is all about “facilitating coordination and cooperation for mutual benefit” ( 2001:67 ). Your literature review can adjudicate among these three approaches, or it can simply refer to the one that is animating your own research. If you include Bourdieu in your literature review, readers will know “what kind” of social capital you are talking about as well as what kind of social scientist you yourself are. They will likely understand that you are interested more in how some people are advantaged by their social capital relative to others rather than being interested in the mechanics of how social networks operate.

The literature review thus does two important things for you: firstly, it allows you to acknowledge previous research in your area of interest, thereby situating you within a discipline or body of scholars, and, secondly, it demonstrates that you know what you are talking about. If you present the findings of your research study without including a literature review, it can be like singing into the wind. It sounds nice, but no one really hears it, or if they do catch snippets, they don’t know where it is coming from.

Examples of Literature Reviews

To help you get a grasp of what a good literature review looks like and how it can advance your study, let’s take a look at a few examples.

Reader-Friendly Example: The Power of Peers

The first is by Janice McCabe ( 2016 ) and is from an article on peer networks in the journal Contexts . Contexts presents articles in a relatively reader-friendly format, with the goal of reaching a large audience for interesting sociological research. Read this example carefully and note how easily McCabe is able to convey the relevance of her own work by situating it in the context of previous studies:

Scholars who study education have long acknowledged the importance of peers for students’ well-being and academic achievement. For example, in 1961, James Coleman argued that peer culture within high schools shapes students’ social and academic aspirations and successes. More recently, Judith Rich Harris has drawn on research in a range of areas—from sociological studies of preschool children to primatologists’ studies of chimpanzees and criminologists’ studies of neighborhoods—to argue that peers matter much more than parents in how children “turn out.” Researchers have explored students’ social lives in rich detail, as in Murray Milner’s book about high school students, Freaks, Geeks, and Cool Kids , and Elizabeth Armstrong and Laura Hamilton’s look at college students, Paying for the Party . These works consistently show that peers play a very important role in most students’ lives. They tend, however, to prioritize social over academic influence and to use a fuzzy conception of peers rather than focusing directly on friends—the relationships that should matter most for student success. Social scientists have also studied the power of peers through network analysis, which is based on uncovering the web of connections between people. Network analysis involves visually mapping networks and mathematically comparing their structures (such as the density of ties) and the positions of individuals within them (such as how central a given person is within the network). As Nicholas Christakis and James Fowler point out in their book Connected , network structure influences a range of outcomes, including health, happiness, wealth, weight, and emotions. Given that sociologists have long considered network explanations for social phenomena, it’s surprising that we know little about how college students’ friends impact their experiences. In line with this network tradition, I focus on the structure of friendship networks, constructing network maps so that the differences we see across participants are due to the underlying structure, including each participant’s centrality in their friendship group and the density of ties among their friends. ( 23 )

What did you notice? In her very second sentence, McCabe uses “for example” to introduce a study by Coleman, thereby indicating that she is not going to tell you every single study in this area but is going to tell you that (1) there is a lot of research in this area, (2) it has been going on since at least 1961, and (3) it is still relevant (i.e., recent studies are still being done now). She ends her first paragraph by summarizing the body of literature in this area (after giving you a few examples) and then telling you what may have been (so far) left out of this research. In the second paragraph, she shifts to a separate interesting focus that is related to the first but is also quite distinct. Lit reviews very often include two (or three) distinct strands of literature, the combination of which nicely backgrounds this particular study . In the case of our female gymnast study (above), those two strands might be (1) cultures of silence around sports injuries and (2) the importance of coaches. McCabe concludes her short and sweet literature review with one sentence explaining how she is drawing from both strands of the literature she has succinctly presented for her particular study. This example should show you that literature reviews can be readable, helpful, and powerful additions to your final presentation.

Authoritative Academic Journal Example: Working Class Students’ College Expectations

The second example is more typical of academic journal writing. It is an article published in the British Journal of Sociology of Education by Wolfgang Lehmann ( 2009 ):

Although this increase in post-secondary enrolment and the push for university is evident across gender, race, ethnicity, and social class categories, access to university in Canada continues to be significantly constrained for those from lower socio-economic backgrounds (Finnie, Lascelles, and Sweetman 2005). Rising tuition fees coupled with an overestimation of the cost and an underestimation of the benefits of higher education has put university out of reach for many young people from low-income families (Usher 2005). Financial constraints aside, empirical studies in Canada have shown that the most important predictor of university access is parental educational attainment. Having at least one parent with a university degree significantly increases the likelihood of a young person to attend academic-track courses in high school, have high educational and career aspirations, and ultimately attend university (Andres et al. 1999, 2000; Lehmann 2007a). Drawing on Bourdieu’s various writing on habitus and class-based dispositions (see, for example, Bourdieu 1977, 1990), Hodkinson and Sparkes (1997) explain career decisions as neither determined nor completely rational. Instead, they are based on personal experiences (e.g., through employment or other exposure to occupations) and advice from others. Furthermore, they argue that we have to understand these decisions as pragmatic, rather than rational. They are pragmatic in that they are based on incomplete and filtered information, because of the social context in which the information is obtained and processed. New experiences and information can, however, also be allowed into one’s world, where they gradually or radically transform habitus, which in turn creates the possibility for the formation of new and different dispositions. Encountering a supportive teacher in elementary or secondary school, having ambitious friends, or chance encounters can spark such transformations. Transformations can be confirming or contradictory, they can be evolutionary or dislocating. Working-class students who enter university most certainly encounter such potentially transformative situations. Granfield (1991) has shown how initially dislocating feelings of inadequacy and inferiority of working-class students at an elite US law school were eventually replaced by an evolutionary transformation, in which the students came to dress, speak and act more like their middle-class and upper-class peers. In contrast, Lehmann (2007b) showed how persistent habitus dislocation led working-class university students to drop out of university. Foskett and Hemsley-Brown (1999) argue that young people’s perceptions of careers are a complex mix of their own experiences, images conveyed through adults, and derived images conveyed by the media. Media images of careers, perhaps, are even more important for working-class youth with high ambitions as they offer (generally distorted) windows into a world of professional employment to which they have few other sources of access. It has also been argued that working-class youth who do continue to university still face unique, class-specific challenges, evident in higher levels of uncertainty (Baxter and Britton 2001; Lehmann 2004, 2007a; Quinn 2004), their higher education choices (Ball et al. 2002; Brooks 2003; Reay et al. 2001) and fears of inadequacy because of their cultural outsider status (Aries and Seider 2005; Granfield 1991). Although the number of working-class university students in Canada has slowly increased, that of middle-class students at university has risen far more steeply (Knighton and Mizra 2002). These different enrolment trajectories have actually widened the participation gap, which in tum explains our continued concerns with the potential outsider status Indeed, in a study comparing first-generation working-class and traditional students who left university without graduating, Lehmann (2007b) found that first-generation working-class students were more likely to leave university very early in some cases within the first two months of enrollment. They were also more likely to leave university despite solid academic performance. Not “fitting in,” not “feeling university,” and not being able to “relate to these people” were key reasons for eventually withdrawing from university. From the preceding review of the literature, a number of key research questions arise: How do working-class university students frame their decision to attend university? How do they defy the considerable odds documented in the literature to attend university? What are the sources of information and various images that create dispositions to study at university? What role does their social-class background- or habitus play in their transition dispositions and how does this translate into expectations for university? ( 139 )

What did you notice here? How is this different from (and similar to) the first example? Note that rather than provide you with one or two illustrative examples of similar types of research, Lehmann provides abundant source citations throughout. He includes theory and concepts too. Like McCabe, Lehmann is weaving through multiple literature strands: the class gap in higher education participation in Canada, class-based dispositions, and obstacles facing working-class college students. Note how he concludes the literature review by placing his research questions in context.

Find other articles of interest and read their literature reviews carefully. I’ve included two more for you at the end of this chapter . As you learned how to diagram a sentence in elementary school (hopefully!), try diagramming the literature reviews. What are the “different strands” of research being discussed? How does the author connect these strands to their own research questions? Where is theory in the lit review, and how is it incorporated (e.g., Is it a separate strand of its own or is it inextricably linked with previous research in this area)?

One model of how to structure your literature review can be found in table 9.1. More tips, hints, and practices will be discussed later in the chapter.

Table 9.1. Model of Literature Review, Adopted from Calarco (2020:166)

Embracing Theory

A good research study will, in some form or another, use theory. Depending on your particular study (and possibly the preferences of the members of your committee), theory may be built into your literature review. Or it may form its own section in your research proposal/design (e.g., “literature review” followed by “theoretical framework”). In my own experience, I see a lot of graduate students grappling with the requirement to “include theory” in their research proposals. Things get a little squiggly here because there are different ways of incorporating theory into a study (Are you testing a theory? Are you generating a theory?), and based on these differences, your literature review proper may include works that describe, explain, and otherwise set forth theories, concepts, or frameworks you are interested in, or it may not do this at all. Sometimes a literature review sets forth what we know about a particular group or culture totally independent of what kinds of theoretical framework or particular concepts you want to explore. Indeed, the big point of your study might be to bring together a body of work with a theory that has never been applied to it previously. All this is to say that there is no one correct way to approach the use of theory and the writing about theory in your research proposal.

Students are often scared of embracing theory because they do not exactly understand what it is. Sometimes, it seems like an arbitrary requirement. You’re interested in a topic; maybe you’ve even done some research in the area and you have findings you want to report. And then a committee member reads over what you have and asks, “So what?” This question is a good clue that you are missing theory, the part that connects what you have done to what other researchers have done and are doing. You might stumble upon this rather accidentally and not know you are embracing theory, as in a case where you seek to replicate a prior study under new circumstances and end up finding that a particular correlation between behaviors only happens when mediated by something else. There’s theory in there, if you can pull it out and articulate it. Or it might be that you are motivated to do more research on racial microaggressions because you want to document their frequency in a particular setting, taking for granted the kind of critical race theoretical framework that has done the hard work of defining and conceptualizing “microaggressions” in the first place. In that case, your literature review could be a review of Critical Race Theory, specifically related to this one important concept. That’s the way to bring your study into a broader conversation while also acknowledging (and honoring) the hard work that has preceded you.

Rubin ( 2021 ) classifies ways of incorporating theory into case study research into four categories, each of which might be discussed somewhat differently in a literature review or theoretical framework section. The first, the least theoretical, is where you set out to study a “configurative idiographic case” ( 70 ) This is where you set out to describe a particular case, leaving yourself pretty much open to whatever you find. You are not expecting anything based on previous literature. This is actually pretty weak as far as research design goes, but it is probably the default for novice researchers. Your committee members should probably help you situate this in previous literature in some way or another. If they cannot, and it really does appear you are looking at something fairly new that no one else has bothered to research before, and you really are completely open to discovery, you might try using a Grounded Theory approach, which is a methodological approach that foregrounds the generation of theory. In that case, your “theory” section can be a discussion of “Grounded Theory” methodology (confusing, yes, but if you take some time to ponder, you will see how this works). You will still need a literature review, though. Ideally one that describes other studies that have ever looked at anything remotely like what you are looking at—parallel cases that have been researched.

The second approach is the “disciplined configurative case,” in which theory is applied to explain a particular case or topic. You are not trying to test the theory but rather assuming the theory is correct, as in the case of exploring microaggressions in a particular setting. In this case, you really do need to have a separate theory section in addition to the literature review, one in which you clearly define the theoretical framework, including any of its important concepts. You can use this section to discuss how other researchers have used the concepts and note any discrepancies in definitions or operationalization of those concepts. This way you will be sure to design your study so that it speaks to and with other researchers. If everyone who is writing about microaggressions has a different definition of them, it is hard for others to compare findings or make any judgments about their prevalence (or any number of other important characteristics). Your literature review section may then stand alone and describe previous research in the particular area or setting, irrespective of the kinds of theory underlying those studies.

The third approach is “heuristic,” one in which you seek to identify new variables, hypotheses, mechanisms, or paths not yet explained by a theory or theoretical framework. In a way, you are generating new theory, but it is probably more accurate to say that you are extending or deepening preexisting theory. In this case, having a single literature review that is focused on the theory and the ways the theory has been applied and understood (with all its various mechanisms and pathways) is probably your best option. The focus of the literature reviewed is less on the case and more on the theory you are seeking to extend.

The final approach is “theory testing,” which is much rarer in qualitative studies than in quantitative, where this is the default approach. Theory-testing cases are those where a particular case is used to see if an existing theory is accurate or accurate under particular circumstances. As with the heuristic approach, your literature review will probably draw heavily on previous uses of the theory, but you may end up having a special section specifically about cases very close to your own . In other words, the more your study approaches theory testing, the more likely there is to be a set of similar studies to draw on or even one important key study that you are setting your own study up in parallel to in order to find out if the theory generated there operates here.

If we wanted to get very technical, it might be useful to distinguish theoretical frameworks properly from conceptual frameworks. The latter are a bit looser and, given the nature of qualitative research, often fit exploratory studies. Theoretical frameworks rely on specific theories and are essential for theory-testing studies. Conceptual frameworks can pull in specific concepts or ideas that may or may not be linked to particular theories. Think about it this way: A theory is a story of how the world works. Concepts don’t presume to explain the whole world but instead are ways to approach phenomena to help make sense of them. Microaggressions are concepts that are linked to Critical Race Theory. One could contextualize one’s study within Critical Race Theory and then draw various concepts, such as that of microaggressions from the overall theoretical framework. Or one could bracket out the master theory or framework and employ the concept of microaggression more opportunistically as a phenomenon of interest. If you are unsure of what theory you are using, you might want to frame a more practical conceptual framework in your review of the literature.

Helpful Tips

How to maintain good notes for what your read.

Over the years, I have developed various ways of organizing notes on what I read. At first, I used a single sheet of full-size paper with a preprinted list of questions and points clearly addressed on the front side, leaving the second side for more reflective comments and free-form musings about what I read, why it mattered, and how it might be useful for my research. Later, I developed a system in which I use a single 4″ × 6″ note card for each book I read. I try only to use the front side (and write very small), leaving the back for comments that are about not just this reading but things to do or examine or consider based on the reading. These notes often mean nothing to anyone else picking up the card, but they make sense to me. I encourage you to find an organizing system that works for you. Then when you set out to compose a literature review, instead of staring at five to ten books or a dozen articles, you will have ten neatly printed pages or notecards or files that have distilled what is important to know about your reading.

It is also a good idea to store this data digitally, perhaps through a reference manager. I use RefWorks, but I also recommend EndNote or any other system that allows you to search institutional databases. Your campus library will probably provide access to one of these or another system. Most systems will allow you to export references from another manager if and when you decide to move to another system. Reference managers allow you to sort through all your literature by descriptor, author, year, and so on. Even so, I personally like to have the ability to manually sort through my index cards, recategorizing things I have read as I go. I use RefWorks to keep a record of what I have read, with proper citations, so I can create bibliographies more easily, and I do add in a few “notes” there, but the bulk of my notes are kept in longhand.

What kinds of information should you include from your reading? Here are some bulleted suggestions from Calarco ( 2020:113–114 ), with my own emendations:

• Citation . If you are using a reference manager, you can import the citation and then, when you are ready to create a bibliography, you can use a provided menu of citation styles, which saves a lot of time. If you’ve originally formatted in Chicago Style but the journal you are writing for wants APA style, you can change your entire bibliography in less than a minute. When using a notecard for a book, I include author, title, date as well as the library call number (since most of what I read I pull from the library). This is something RefWorks is not able to do, and it helps when I categorize.

I begin each notecard with an “intro” section, where I record the aims, goals, and general point of the book/article as explained in the introductory sections (which might be the preface, the acknowledgments, or the first two chapters). I then draw a bold line underneath this part of the notecard. Everything after that should be chapter specific. Included in this intro section are things such as the following, recommended by Calarco ( 2020 ):

• Key background . “Two to three short bullet points identifying the theory/prior research on which the authors are building and defining key terms.”
• Data/methods . “One or two short bullet points with information about the source of the data and the method of analysis, with a note if this is a novel or particularly effective example of that method.” I use [M] to signal methodology on my notecard, which might read, “[M] Int[erview]s (n-35), B[lack]/W[hite] voters” (I need shorthand to fit on my notecard!).
• Research question . “Stated as briefly as possible.” I always provide page numbers so I can go back and see exactly how this was stated (sometimes, in qualitative research, there are multiple research questions, and they cannot be stated simply).
• Argument/contributions . “Two to three short bullet points briefly describing the authors’ answer to the central research question and its implication for research, theory, and practice.” I use [ARG] for argument to signify the argument, and I make sure this is prominently visible on my notecard. I also provide page numbers here.

For me, all of this fits in the “intro” section, which, if this is a theoretically rich, methodologically sound book, might take up a third or even half of the front page of my notecard. Beneath the bold underline, I report specific findings or particulars of the book as they emerge chapter by chapter. Calarco’s ( 2020 ) next step is the following:

• Key findings . “Three to four short bullet points identifying key patterns in the data that support the authors’ argument.”

All that remains is writing down thoughts that occur upon finishing the article/book. I use the back of the notecard for these kinds of notes. Often, they reach out to other things I have read (e.g., “Robinson reminds me of Crusoe here in that both are looking at the effects of social isolation, but I think Robinson makes a stronger argument”). Calarco ( 2020 ) concludes similarly with the following:

• Unanswered questions . “Two to three short bullet points that identify key limitations of the research and/or questions the research did not answer that could be answered in future research.”

As I mentioned, when I first began taking notes like this, I preprinted pages with prompts for “research question,” “argument,” and so on. This was a great way to remind myself to look for these things in particular. You can do the same, adding whatever preprinted sections make sense to you, given what you are studying and the important aspects of your discipline. The other nice thing about the preprinted forms is that it keeps your writing to a minimum—you cannot write more than the allotted space, even if you might want to, preventing your notes from spiraling out of control. This can be helpful when we are new to a subject and everything seems worth recording!

After years of discipline, I have finally settled on my notecard approach. I have thousands of notecards, organized in several index card filing boxes stacked in my office. On the top right of each card is a note of the month/day I finished reading the item. I can remind myself what I read in the summer of 2010 if the need or desire ever arose to do so…those invaluable notecards are like a memento of what my brain has been up to!

Where to Start Looking for Literature

Your university library should provide access to one of several searchable databases for academic books and articles. My own preference is JSTOR, a service of ITHAKA, a not-for-profit organization that works to advance and preserve knowledge and to improve teaching and learning through the use of digital technologies. JSTOR allows you to search by several keywords and to narrow your search by type of material (articles or books). For many disciplines, the “literature” of the literature review is expected to be peer-reviewed “articles,” but some disciplines will also value books and book chapters. JSTOR is particularly useful for article searching. You can submit several keywords and see what is returned, and you can also narrow your search by a particular journal or discipline. If your discipline has one or two key journals (e.g., the American Journal of Sociology and the American Sociological Review are key for sociology), you might want to go directly to those journals’ websites and search for your topic area. There is an art to when to cast your net widely and when to refine your search, and you may have to tack back and forth to ensure that you are getting all that is relevant but not getting bogged down in all studies that might have some marginal relevance.

Some articles will carry more weight than others, and you can use applications like Google Scholar to see which articles have made and are continuing to make larger impacts on your discipline. Find these articles and read them carefully; use their literature review and the sources cited in those articles to make sure you are capturing what is relevant. This is actually a really good way of finding relevant books—only the most impactful will make it into the citations of journals. Over time, you will notice that a handful of articles (or books) are cited so often that when you see, say, Armstrong and Hamilton ( 2015 ), you know exactly what book this is without looking at the full cite. This is when you know you are in the conversation.

You might also approach a professor whose work is broadly in the area of your interest and ask them to recommend one or two “important” foundational articles or books. You can then use the references cited in those recommendations to build up your literature. Just be careful: some older professors’ knowledge of the literature (and I reluctantly add myself here) may be a bit outdated! It is best that the article or book whose references and sources you use to build your body of literature be relatively current.

Keep a List of Your Keywords

When using searchable databases, it is a good idea to keep a list of all the keywords you use as you go along so that (1) you do not needlessly duplicate your efforts and (2) you can more easily adjust your search as you get a better sense of what you are looking for. I suggest you keep a separate file or even a small notebook for this and you date your search efforts.

Here’s an example:

Table 9.2. Keep a List of Your Keywords

Think Laterally

How to find the various strands of literature to combine? Don’t get stuck on finding the exact same research topic you think you are interested in. In the female gymnast example, I recommended that my student consider looking for studies of ballerinas, who also suffer sports injuries and around whom there is a similar culture of silence. It turned out that there was in fact research about my student’s particular questions, just not about the subjects she was interested in. You might do something similar. Don’t get stuck looking for too direct literature but think about the broader phenomenon of interest or analogous cases.

Read Outside the Canon

Some scholars’ work gets cited by everyone all the time. To some extent, this is a very good thing, as it helps establish the discipline. For example, there are a lot of “Bourdieu scholars” out there (myself included) who draw ideas, concepts, and quoted passages from Bourdieu. This makes us recognizable to one another and is a way of sharing a common language (e.g., where “cultural capital” has a particular meaning to those versed in Bourdieusian theory). There are empirical studies that get cited over and over again because they are excellent studies but also because there is an “echo chamber effect” going on, where knowing to cite this study marks you as part of the club, in the know, and so on. But here’s the problem with this: there are hundreds if not thousands of excellent studies out there that fail to get appreciated because they are crowded out by the canon. Sometimes this happens because they are published in “lower-ranked” journals and are never read by a lot of scholars who don’t have time to read anything other than the “big three” in their field. Other times this happens because the author falls outside of the dominant social networks in the field and thus is unmentored and fails to get noticed by those who publish a lot in those highly ranked and visible spaces. Scholars who fall outside the dominant social networks and who publish outside of the top-ranked journals are in no way less insightful than their peers, and their studies may be just as rigorous and relevant to your work, so it is important for you to take some time to read outside the canon. Due to how a person’s race, gender, and class operate in the academy, there is also a matter of social justice and ethical responsibility involved here: “When you focus on the most-cited research, you’re more likely to miss relevant research by women and especially women of color, whose research tends to be under-cited in most fields. You’re also more likely to miss new research, research by junior scholars, and research in other disciplines that could inform your work. Essentially, it is important to read and cite responsibly, which means checking that you’re not just reading and citing the same white men and the same old studies that everyone has cited before you” ( Calarco 2020:112 ).

Consider Multiple Uses for Literature

Throughout this chapter, I’ve referred to the literature of interest in a rather abstract way, as what is relevant to your study. But there are many different ways previous research can be relevant to your study. The most basic use of the literature is the “findings”—for example, “So-and-so found that Canadian working-class students were concerned about ‘fitting in’ to the culture of college, and I am going to look at a similar question here in the US.” But the literature may be of interest not for its findings but theoretically—for example, employing concepts that you want to employ in your own study. Bourdieu’s definition of social capital may have emerged in a study of French professors, but it can still be relevant in a study of, say, how parents make choices about what preschools to send their kids to (also a good example of lateral thinking!).

If you are engaged in some novel methodological form of data collection or analysis, you might look for previous literature that has attempted that. I would not recommend this for undergraduate research projects, but for graduate students who are considering “breaking the mold,” find out if anyone has been there before you. Even if their study has absolutely nothing else in common with yours, it is important to acknowledge that previous work.

Describing Gaps in the Literature

First, be careful! Although it is common to explain how your research adds to, builds upon, and fills in gaps in the previous research (see all four literature review examples in this chapter for this), there is a fine line between describing the gaps and misrepresenting previous literature by failing to conduct a thorough review of the literature. A little humility can make a big difference in your presentation. Instead of “This is the first study that has looked at how firefighters juggle childcare during forest fire season,” say, “I use the previous literature on how working parents juggling childcare and the previous ethnographic studies of firefighters to explore how firefighters juggle childcare during forest fire season.” You can even add, “To my knowledge, no one has conducted an ethnographic study in this specific area, although what we have learned from X about childcare and from Y about firefighters would lead us to expect Z here.” Read more literature review sections to see how others have described the “gaps” they are filling.

Use Concept Mapping

Concept mapping is a helpful tool for getting your thoughts in order and is particularly helpful when thinking about the “literature” foundational to your particular study. Concept maps are also known as mind maps, which is a delightful way to think about them. Your brain is probably abuzz with competing ideas in the early stages of your research design. Write/draw them on paper, and then try to categorize and move the pieces around into “clusters” that make sense to you. Going back to the gymnasts example, my student might have begun by jotting down random words of interest: gymnasts * sports * coaches * female gymnasts * stress * injury * don’t complain * women in sports * bad coaching * anxiety/stress * careers in sports * pain. She could then have begun clustering these into relational categories (bad coaching, don’t complain culture) and simple “event” categories (injury, stress). This might have led her to think about reviewing literature in these two separate aspects and then literature that put them together. There is no correct way to draw a concept map, as they are wonderfully specific to your mind. There are many examples you can find online.

Ask Yourself, “How Is This Sociology (or Political Science or Public Policy, Etc.)?”

Rubin ( 2021:82 ) offers this suggestion instead of asking yourself the “So what?” question to get you thinking about what bridges there are between your study and the body of research in your particular discipline. This is particularly helpful for thinking about theory. Rubin further suggests that if you are really stumped, ask yourself, “What is the really big question that all [fill in your discipline here] care about?” For sociology, it might be “inequality,” which would then help you think about theories of inequality that might be helpful in framing your study on whatever it is you are studying—OnlyFans? Childcare during COVID? Aging in America? I can think of some interesting ways to frame questions about inequality for any of those topics. You can further narrow it by focusing on particular aspects of inequality (Gender oppression? Racial exclusion? Heteronormativity?). If your discipline is public policy, the big questions there might be, How does policy get enacted, and what makes a policy effective? You can then take whatever your particular policy interest is—tax reform, student debt relief, cap-and-trade regulations—and apply those big questions. Doing so would give you a handle on what is otherwise an intolerably vague subject (e.g., What about student debt relief?).

Sometimes finding you are in new territory means you’ve hit the jackpot, and sometimes it means you’ve traveled out of bounds for your discipline. The jackpot scenario is wonderful. You are doing truly innovative research that is combining multiple literatures or is addressing a new or under-examined phenomenon of interest, and your research has the potential to be groundbreaking. Congrats! But that’s really hard to do, and it might be more likely that you’ve traveled out of bounds, by which I mean, you are no longer in your discipline . It might be that no one has written about this thing—at least within your field— because no one in your field actually cares about this topic . ( Rubin 2021:83 ; emphases added)

Don’t Treat This as a Chore

Don’t treat the literature review as a chore that has to be completed, but see it for what it really is—you are building connections to other researchers out there. You want to represent your discipline or area of study fairly and adequately. Demonstrate humility and your knowledge of previous research. Be part of the conversation.

Supplement: Two More Literature Review Examples

Elites by harvey ( 2011 ).

In the last two decades, there has been a small but growing literature on elites. In part, this has been a result of the resurgence of ethnographic research such as interviews, focus groups, case studies, and participant observation but also because scholars have become increasingly interested in understanding the perspectives and behaviors of leaders in business, politics, and society as a whole. Yet until recently, our understanding of some of the methodological challenges of researching elites has lagged behind our rush to interview them.

There is no clear-cut definition of the term elite, and given its broad understanding across the social sciences, scholars have tended to adopt different approaches. Zuckerman (1972) uses the term ultraelites to describe individuals who hold a significant amount of power within a group that is already considered elite. She argues, for example, that US senators constitute part of the country’s political elite but that among them are the ultraelites: a “subset of particularly powerful or prestigious influentials” (160). She suggests that there is a hierarchy of status within elite groups. McDowell (1998) analyses a broader group of “professional elites” who are employees working at different levels for merchant and investment banks in London. She classifies this group as elite because they are “highly skilled, professionally competent, and class-specific” (2135). Parry (1998:2148) uses the term hybrid elites in the context of the international trade of genetic material because she argues that critical knowledge exists not in traditional institutions “but rather as increasingly informal, hybridised, spatially fragmented, and hence largely ‘invisible,’ networks of elite actors.” Given the undertheorization of the term elite, Smith (2006) recognizes why scholars have shaped their definitions to match their respondents . However, she is rightly critical of the underlying assumption that those who hold professional positions necessarily exert as much influence as initially perceived. Indeed, job titles can entirely misrepresent the role of workers and therefore are by no means an indicator of elite status (Harvey 2010).

Many scholars have used the term elite in a relational sense, defining them either in terms of their social position compared to the researcher or compared to the average person in society (Stephens 2007). The problem with this definition is there is no guarantee that an elite subject will necessarily translate this power and authority in an interview setting. Indeed, Smith (2006) found that on the few occasions she experienced respondents wanting to exert their authority over her, it was not from elites but from relatively less senior workers. Furthermore, although business and political elites often receive extensive media training, they are often scrutinized by television and radio journalists and therefore can also feel threatened in an interview, particularly in contexts that are less straightforward to prepare for such as academic interviews. On several occasions, for instance, I have been asked by elite respondents or their personal assistants what they need to prepare for before the interview, which suggests that they consider the interview as some form of challenge or justification for what they do.

In many cases, it is not necessarily the figureheads or leaders of organizations and institutions who have the greatest claim to elite status but those who hold important social networks, social capital, and strategic positions within social structures because they are better able to exert influence (Burt 1992; Parry 1998; Smith 2005; Woods 1998). An elite status can also change, with people both gaining and losing theirs over time. In addition, it is geographically specific, with people holding elite status in some but not all locations. In short, it is clear that the term elite can mean many things in different contexts, which explains the range of definitions. The purpose here is not to critique these other definitions but rather to highlight the variety of perspectives.

When referring to my research, I define elites as those who occupy senior-management- and board-level positions within organizations. This is a similar scope of definition to Zuckerman’s (1972) but focuses on a level immediately below her ultraelite subjects. My definition is narrower than McDowell’s (1998) because it is clear in the context of my research that these people have significant decision-making influence within and outside of the firm and therefore present a unique challenge to interview. I deliberately use the term elite more broadly when drawing on examples from the theoretical literature in order to compare my experiences with those who have researched similar groups.

”Changing Dispositions among the Upwardly Mobile” by Curl, Lareau, and Wu ( 2018 )

There is growing interest in the role of cultural practices in undergirding the social stratification system. For example, Lamont et al. (2014) critically assess the preoccupation with economic dimensions of social stratification and call for more developed cultural models of the transmission of inequality. The importance of cultural factors in the maintenance of social inequality has also received empirical attention from some younger scholars, including Calarco (2011, 2014) and Streib (2015). Yet questions remain regarding the degree to which economic position is tied to cultural sensibilities and the ways in which these cultural sensibilities are imprinted on the self or are subject to change. Although habitus is a core concept in Bourdieu’s theory of social reproduction, there is limited empirical attention to the precise areas of the habitus that can be subject to change during upward mobility as well as the ramifications of these changes for family life.

In Bourdieu’s (1984) highly influential work on the importance of class-based cultural dispositions, habitus is defined as a “durable system of dispositions” created in childhood. The habitus provides a “matrix of perceptions” that seems natural while also structuring future actions and pathways. In many of his writings, Bourdieu emphasized the durability of cultural tastes and dispositions and did not consider empirically whether these dispositions might be changed or altered throughout one’s life (Swartz 1997). His theoretical work does permit the possibility of upward mobility and transformation, however, through the ability of the habitus to “improvise” or “change” due to “new experiences” (Friedman 2016:131). Researchers have differed in opinion on the durability of the habitus and its ability to change (King 2000). Based on marital conflict in cross-class marriages, for instance, Streib (2015) argues that cultural dispositions of individuals raised in working-class families are deeply embedded and largely unchanging. In a somewhat different vein, Horvat and Davis (2011:152) argue that young adults enrolled in an alternative educational program undergo important shifts in their self-perception, such as “self-esteem” and their “ability to accomplish something of value.” Others argue there is variability in the degree to which habitus changes dependent on life experience and personality (Christodoulou and Spyridakis 2016). Recently, additional studies have investigated the habitus as it intersects with lifestyle through the lens of meaning making (Ambrasat et al. 2016). There is, therefore, ample discussion of class-based cultural practices in self-perception (Horvat and Davis 2011), lifestyle (Ambrasat et al. 2016), and other forms of taste (Andrews 2012; Bourdieu 1984), yet researchers have not sufficiently delineated which aspects of the habitus might change through upward mobility or which specific dimensions of life prompt moments of class-based conflict.

Bourdieu (1999:511; 2004) acknowledged simmering tensions between the durable aspects of habitus and those aspects that have been transformed—that is, a “fractured” or “cleft” habitus. Others have explored these tensions as a “divided” or “fragmented” habitus (Baxter and Britton 2001; Lee and Kramer 2013). Each of these conceptions of the habitus implies that changes in cultural dispositions are possible but come with costs. Exploration of the specific aspects of one’s habitus that can change and generate conflict contributes to this literature.

Scholars have also studied the costs associated with academic success for working-class undergraduates (Hurst 2010; Lee and Kramer 2013; London 1989; Reay 2017; Rondini 2016; Stuber 2011), but we know little about the lasting effects on adults. For instance, Lee and Kramer (2013) point to cross-class tensions as family and friends criticize upwardly mobile individuals for their newly acquired cultural dispositions. Documenting the tension many working-class students experience with their friends and families of origin, they find that the source of their pain or struggle is “shaped not only by their interactions with non-mobile family and friends but also within their own minds, by their own assessments of their social positions, and by how those positions are interpreted by others” (Lee and Kramer 2013:29). Hurst (2010) also explores the experiences of undergraduates who have been academically successful and the costs associated with that success. She finds that decisions about “class allegiance and identity” are required aspects of what it means to “becom[e] educated” (4) and that working-class students deal with these cultural changes differently. Jack (2014, 2016) also argues that there is diversity among lower-income students, which yields varied college experiences. Naming two groups, the “doubly disadvantaged” and the “privileged poor,” he argues that previous experience with “elite environments” (2014:456) prior to college informs students’ ability to take on dominant cultural practices, particularly around engagement, such as help seeking or meeting with professors (2016). These studies shed light on the role college might play as a “lever for mobility” (2016:15) and discuss the pain and difficulty associated with upward mobility among undergraduates, but the studies do not illuminate how these tensions unfold in adulthood. Neither have they sufficiently addressed potential enduring tensions with extended family members as well as the specific nature of the difficulties.

Some scholars point to the positive outcomes upwardly mobile youth (Lehmann 2009) and adults (Stuber 2005) experience when they maintain a different habitus than their newly acquired class position, although, as Jack (2014, 2016) shows, those experiences may vary depending on one’s experience with elite environments in their youth. Researchers have not sufficiently explored the specific aspects of the habitus that upwardly mobile adults change or the conflicts that emerge with family and childhood friends as they reach adulthood and experience colliding social worlds. We contribute to this scholarship with clear examples of self-reported changes to one’s cultural dispositions in three specific areas: “horizons,” food and health, and communication. We link these changes to enduring tension with family members, friends, and colleagues and explore varied responses to this tension based on race.

Further Readings

Bloomberg, Linda Dale, and Marie F. Volpe. 2012. Completing Your Qualitative Dissertation: A Road Map from Beginning to End . 2nd ed. Thousand Oaks, CA: SAGE. In keeping with its general approach to qualitative research, includes a “road map” for conducting a literature review.

Hart, Chris. 1998. Doing a Literature Review: Releasing the Social Science Research Imagination . London: SAGE. A how-to book dedicated entirely to conducting a literature review from a British perspective. Useful for both undergraduate and graduate students.

Machi, Lawrence A., and Brenda T. McEvoy. 2022. The Literature Review: Six Steps to Success . 4th ed. Newbury Park, CA: Corwin. A well-organized guidebook complete with reflection sections to prompt successful thinking about your literature review.

Ridley, Diana. 2008. The Literature Review: A Step-by-Step Guide for Students . London: SAGE. A highly recommended companion to conducting a literature review for doctoral-level students.

The process of systematically searching through pre-existing studies (“literature”) on the subject of research; also, the section of a presentation in which the pre-existing literature is discussed.

Follow-up questions used in a semi-structured interview  to elicit further elaboration.  Suggested prompts can be included in the interview guide  to be used/deployed depending on how the initial question was answered or if the topic of the prompt does not emerge spontaneously.

A tool for identifying relationships among ideas by visually representing them on paper.  Most concept maps depict ideas as boxes or circles (also called nodes), which are structured hierarchically and connected with lines or arrows (also called arcs). These lines are labeled with linking words and phrases to help explain the connections between concepts.  Also known as mind mapping.

The people who are the subjects of an interview-based qualitative study. In general, they are also known as the participants, and for purposes of IRBs they are often referred to as the human subjects of the research.

Introduction to Qualitative Research Methods Copyright © 2023 by Allison Hurst is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License , except where otherwise noted.

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Chapter 2: Getting Started in Research

Reviewing the Research Literature

Learning Objectives

• Define the research literature in psychology and give examples of sources that are part of the research literature and sources that are not.
• Describe and use several methods for finding previous research on a particular research idea or question.

Reviewing the research literature means finding, reading, and summarizing the published research relevant to your question. An empirical research report written in American Psychological Association (APA) style always includes a written literature review, but it is important to review the literature early in the research process for several reasons.

• It can help you turn a research idea into an interesting research question.
• It can tell you if a research question has already been answered.
• It can help you evaluate the interestingness of a research question.
• It can give you ideas for how to conduct your own study.
• It can tell you how your study fits into the research literature.

What Is the Research Literature?

The  research literature  in any field is all the published research in that field. The research literature in psychology is enormous—including millions of scholarly articles and books dating to the beginning of the field—and it continues to grow. Although its boundaries are somewhat fuzzy, the research literature definitely does not include self-help and other pop psychology books, dictionary and encyclopedia entries, websites, and similar sources that are intended mainly for the general public. These are considered unreliable because they are not reviewed by other researchers and are often based on little more than common sense or personal experience. Wikipedia contains much valuable information, but the fact that its authors are anonymous and may not have any formal training or expertise in that subject area, and its content continually changes makes it unsuitable as a basis of sound scientific research. For our purposes, it helps to define the research literature as consisting almost entirely of two types of sources: articles in professional journals, and scholarly books in psychology and related fields.

Professional Journals

Professional journals  are periodicals that publish original research articles. There are thousands of professional journals that publish research in psychology and related fields. They are usually published monthly or quarterly in individual issues, each of which contains several articles. The issues are organized into volumes, which usually consist of all the issues for a calendar year. Some journals are published in hard copy only, others in both hard copy and electronic form, and still others in electronic form only.

Most articles in professional journals are one of two basic types: empirical research reports and review articles.  Empirical research reports  describe one or more new empirical studies conducted by the authors. They introduce a research question, explain why it is interesting, review previous research, describe their method and results, and draw their conclusions. Review articles  summarize previously published research on a topic and usually present new ways to organize or explain the results. When a review article is devoted primarily to presenting a new theory, it is often referred to as a theoretical article .

Most professional journals in psychology undergo a process of  double-blind peer review . Researchers who want to publish their work in the journal submit a manuscript to the editor—who is generally an established researcher too—who in turn sends it to two or three experts on the topic. Each reviewer reads the manuscript, writes a critical but constructive review, and sends the review back to the editor along with his or her recommendations. The editor then decides whether to accept the article for publication, ask the authors to make changes and resubmit it for further consideration, or reject it outright. In any case, the editor forwards the reviewers’ written comments to the researchers so that they can revise their manuscript accordingly. This entire process is double-blind, as the reviewers do not know the identity of the researcher(s), and vice versa. Double-blind peer review is helpful because it ensures that the work meets basic standards of the field before it can enter the research literature. However, in order to increase transparency and accountability some newer open access journals (e.g., Frontiers in Psychology) utilize an open peer review process wherein the identities of the reviewers (which remain concealed during the peer review process) are published alongside the journal article.

Scholarly Books

Scholarly books  are books written by researchers and practitioners mainly for use by other researchers and practitioners. A  monograph  is written by a single author or a small group of authors and usually gives a coherent presentation of a topic much like an extended review article.  Edited volumes have an editor or a small group of editors who recruit many authors to write separate chapters on different aspects of the same topic. Although edited volumes can also give a coherent presentation of the topic, it is not unusual for each chapter to take a different perspective or even for the authors of different chapters to openly disagree with each other. In general, scholarly books undergo a peer review process similar to that used by professional journals.

Literature Search Strategies

Using psycinfo and other databases.

The primary method used to search the research literature involves using one or more electronic databases. These include Academic Search Premier, JSTOR, and ProQuest for all academic disciplines, ERIC for education, and PubMed for medicine and related fields. The most important for our purposes, however, is PsycINFO, which is produced by the APA. PsycINFO is so comprehensive—covering thousands of professional journals and scholarly books going back more than 100 years—that for most purposes its content is synonymous with the research literature in psychology. Like most such databases, PsycINFO is usually available through your university library.

PsycINFO consists of individual records for each article, book chapter, or book in the database. Each record includes basic publication information, an abstract or summary of the work (like the one presented at the start of this chapter), and a list of other works cited by that work. A computer interface allows entering one or more search terms and returns any records that contain those search terms. (These interfaces are provided by different vendors and therefore can look somewhat different depending on the library you use.) Each record also contains lists of keywords that describe the content of the work and also a list of index terms. The index terms are especially helpful because they are standardized. Research on differences between women and men, for example, is always indexed under “Human Sex Differences.” Research on notetaking is always indexed under the term “Learning Strategies.” If you do not know the appropriate index terms, PsycINFO includes a thesaurus that can help you find them.

Given that there are nearly four million records in PsycINFO, you may have to try a variety of search terms in different combinations and at different levels of specificity before you find what you are looking for. Imagine, for example, that you are interested in the question of whether women and men differ in terms of their ability to recall experiences from when they were very young. If you were to enter “memory for early experiences” as your search term, PsycINFO would return only six records, most of which are not particularly relevant to your question. However, if you were to enter the search term “memory,” it would return 149,777 records—far too many to look through individually. This is where the thesaurus helps. Entering “memory” into the thesaurus provides several more specific index terms—one of which is “early memories.” While searching for “early memories” among the index terms returns 1,446 records—still too many too look through individually—combining it with “human sex differences” as a second search term returns 37 articles, many of which are highly relevant to the topic.

Depending on the vendor that provides the interface to PsycINFO, you may be able to save, print, or e-mail the relevant PsycINFO records. The records might even contain links to full-text copies of the works themselves. (PsycARTICLES is a database that provides full-text access to articles in all journals published by the APA.) If not, and you want a copy of the work, you will have to find out if your library carries the journal or has the book and the hard copy on the library shelves. Be sure to ask a librarian if you need help.

Using Other Search Techniques

In addition to entering search terms into PsycINFO and other databases, there are several other techniques you can use to search the research literature. First, if you have one good article or book chapter on your topic—a recent review article is best—you can look through the reference list of that article for other relevant articles, books, and book chapters. In fact, you should do this with any relevant article or book chapter you find. You can also start with a classic article or book chapter on your topic, find its record in PsycINFO (by entering the author’s name or article’s title as a search term), and link from there to a list of other works in PsycINFO that cite that classic article. This works because other researchers working on your topic are likely to be aware of the classic article and cite it in their own work. You can also do a general Internet search using search terms related to your topic or the name of a researcher who conducts research on your topic. This might lead you directly to works that are part of the research literature (e.g., articles in open-access journals or posted on researchers’ own websites). The search engine Google Scholar is especially useful for this purpose. A general Internet search might also lead you to websites that are not part of the research literature but might provide references to works that are. Finally, you can talk to people (e.g., your instructor or other faculty members in psychology) who know something about your topic and can suggest relevant articles and book chapters.

What to Search For

When you do a literature review, you need to be selective. Not every article, book chapter, and book that relates to your research idea or question will be worth obtaining, reading, and integrating into your review. Instead, you want to focus on sources that help you do four basic things: (a) refine your research question, (b) identify appropriate research methods, (c) place your research in the context of previous research, and (d) write an effective research report. Several basic principles can help you find the most useful sources.

First, it is best to focus on recent research, keeping in mind that what counts as recent depends on the topic. For newer topics that are actively being studied, “recent” might mean published in the past year or two. For older topics that are receiving less attention right now, “recent” might mean within the past 10 years. You will get a feel for what counts as recent for your topic when you start your literature search. A good general rule, however, is to start with sources published in the past five years. The main exception to this rule would be classic articles that turn up in the reference list of nearly every other source. If other researchers think that this work is important, even though it is old, then by all means you should include it in your review.

Second, you should look for review articles on your topic because they will provide a useful overview of it—often discussing important definitions, results, theories, trends, and controversies—giving you a good sense of where your own research fits into the literature. You should also look for empirical research reports addressing your question or similar questions, which can give you ideas about how to operationally define your variables and collect your data. As a general rule, it is good to use methods that others have already used successfully unless you have good reasons not to. Finally, you should look for sources that provide information that can help you argue for the interestingness of your research question. For a study on the effects of cell phone use on driving ability, for example, you might look for information about how widespread cell phone use is, how frequent and costly motor vehicle crashes are, and so on.

How many sources are enough for your literature review? This is a difficult question because it depends on how extensively your topic has been studied and also on your own goals. One study found that across a variety of professional journals in psychology, the average number of sources cited per article was about 50 (Adair & Vohra, 2003) [1] . This gives a rough idea of what professional researchers consider to be adequate. As a student, you might be assigned a much lower minimum number of references to use, but the principles for selecting the most useful ones remain the same.

Key Takeaways

• The research literature in psychology is all the published research in psychology, consisting primarily of articles in professional journals and scholarly books.
• Early in the research process, it is important to conduct a review of the research literature on your topic to refine your research question, identify appropriate research methods, place your question in the context of other research, and prepare to write an effective research report.
• There are several strategies for finding previous research on your topic. Among the best is using PsycINFO, a computer database that catalogs millions of articles, books, and book chapters in psychology and related fields.
• Practice: Use the techniques discussed in this section to find 10 journal articles and book chapters on one of the following research ideas: memory for smells, aggressive driving, the causes of narcissistic personality disorder, the functions of the intraparietal sulcus, or prejudice against the physically handicapped.
• Watch the following video clip produced by UBCiSchool about how to read an academic paper (without losing your mind):

Video Attributions

• “ Sample PsycINFO Search on EBSCOhost ” by APA Publishing Training . Standard YouTube Licence.
• “ Using Google Scholar (CLIP) ” by clipinfolit . CC BY (Attribution)
• “ How to Read an Academic Paper ” by UBCiSchool . CC BY (Attribution)
• Adair, J. G., & Vohra, N. (2003). The explosion of knowledge, references, and citations: Psychology’s unique response to a crisis. American Psychologist, 58 , 15–23. ↵

All the published research in a particular field.

Periodicals that publish original research articles.

A type of research article which describes one or more new empirical studies conducted by the authors.

A type of research article that summarizes previously published research on a topic and usually presents new ways to organize or explain the results.

A type of review article primarily devoted to presenting a new theory.

Books written by researchers and practitioners mainly for sue by other researchers and practitioners.

Type of scholarly book written by a single author or small group of authors, coherently presents a topic much like an extended review article.

A type of scholarly book in which an editor or small group of editors recruit many authors to write separate chapters on different aspects of the same topic.

An electronic database covering thousands of professional journals and scholarly books produced by the APA.

Research Methods in Psychology - 2nd Canadian Edition Copyright © 2015 by Paul C. Price, Rajiv Jhangiani, & I-Chant A. Chiang is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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• Writing Tips

What is the Purpose of a Literature Review?

4-minute read

• 23rd October 2023

If you’re writing a research paper or dissertation , then you’ll most likely need to include a comprehensive literature review . In this post, we’ll review the purpose of literature reviews, why they are so significant, and the specific elements to include in one. Literature reviews can:

1. Provide a foundation for current research.

2. Define key concepts and theories.

3. Demonstrate critical evaluation.

4. Show how research and methodologies have evolved.

5. Identify gaps in existing research.

6. Support your argument.

Keep reading to enter the exciting world of literature reviews!

What is a Literature Review?

A literature review is a critical summary and evaluation of the existing research (e.g., academic journal articles and books) on a specific topic. It is typically included as a separate section or chapter of a research paper or dissertation, serving as a contextual framework for a study. Literature reviews can vary in length depending on the subject and nature of the study, with most being about equal length to other sections or chapters included in the paper. Essentially, the literature review highlights previous studies in the context of your research and summarizes your insights in a structured, organized format. Next, let’s look at the overall purpose of a literature review.

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Literature reviews are considered an integral part of research across most academic subjects and fields. The primary purpose of a literature review in your study is to:

Provide a Foundation for Current Research

Since the literature review provides a comprehensive evaluation of the existing research, it serves as a solid foundation for your current study. It’s a way to contextualize your work and show how your research fits into the broader landscape of your specific area of study.  

Define Key Concepts and Theories

The literature review highlights the central theories and concepts that have arisen from previous research on your chosen topic. It gives your readers a more thorough understanding of the background of your study and why your research is particularly significant .

Demonstrate Critical Evaluation 

A comprehensive literature review shows your ability to critically analyze and evaluate a broad range of source material. And since you’re considering and acknowledging the contribution of key scholars alongside your own, it establishes your own credibility and knowledge.

Show How Research and Methodologies Have Evolved

Another purpose of literature reviews is to provide a historical perspective and demonstrate how research and methodologies have changed over time, especially as data collection methods and technology have advanced. And studying past methodologies allows you, as the researcher, to understand what did and did not work and apply that knowledge to your own research.  

Identify Gaps in Existing Research

Besides discussing current research and methodologies, the literature review should also address areas that are lacking in the existing literature. This helps further demonstrate the relevance of your own research by explaining why your study is necessary to fill the gaps.

Support Your Argument

A good literature review should provide evidence that supports your research questions and hypothesis. For example, your study may show that your research supports existing theories or builds on them in some way. Referencing previous related studies shows your work is grounded in established research and will ultimately be a contribution to the field.  

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Ensure your literature review is polished and ready for submission by having it professionally proofread and edited by our expert team. Our literature review editing services will help your research stand out and make an impact. Not convinced yet? Send in your free sample today and see for yourself! 

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• Open access
• Published: 30 May 2024

Barriers and facilitators to mental health treatment access and engagement for LGBTQA+ people with psychosis: a scoping review protocol

• Cláudia C. Gonçalves   ORCID: orcid.org/0000-0001-6767-0920 1 ,
• Zoe Waters 2 ,
• Shae E. Quirk 1 ,
• Peter M. Haddad 1 , 3 ,
• Ashleigh Lin 4 ,
• Lana J. Williams 1 &
• Alison R. Yung 1 , 5  

Systematic Reviews volume  13 , Article number:  143 ( 2024 ) Cite this article

78 Accesses

Metrics details

The prevalence of psychosis has been shown to be disproportionately high amongst sexual and gender minority individuals. However, there is currently little consideration of the unique needs of this population in mental health treatment, with LGBTQA+ individuals facing barriers in accessing timely and non-stigmatising support for psychotic experiences. This issue deserves attention as delays to help-seeking and poor engagement with treatment predict worsened clinical and functional outcomes for people with psychosis. The present protocol describes the methodology for a scoping review which will aim to identify barriers and facilitators faced by LGBTQA+ individuals across the psychosis spectrum in help-seeking and accessing mental health support.

A comprehensive search strategy will be used to search Medline, PsycINFO, Embase, Scopus, LGBTQ+ Source, and grey literature. Original studies of any design, setting, and publication date will be included if they discuss barriers and facilitators to mental health treatment access and engagement for LGBTQA+ people with experiences of psychosis. Two reviewers will independently screen titles/abstracts and full-text articles for inclusion in the review. Both reviewers will then extract the relevant data according to pre-determined criteria, and study quality will be assessed using the Joanna Briggs Institute (JBI) critical appraisal checklists. Key data from included studies will be synthesised in narrative form according to the Guidance on the Conduct of Narrative Synthesis in Systematic Reviews.

The results of this review will provide a comprehensive account of the current and historical barriers and facilitators to mental healthcare faced by LGBTQA+ people with psychotic symptoms and experiences. It is anticipated that the findings from this review will be relevant to clinical and community services and inform future research. Findings will be disseminated through publication in a peer-reviewed journal and presented at conferences.

Scoping review registration

This protocol is registered in Open Science Framework Registries ( https://doi.org/10.17605/OSF.IO/AT6FC ).

Peer Review reports

The prevalence of psychotic disorders in the general population has been estimated to be around 0.27–0.75% [ 1 , 2 ], with the lifetime prevalence of ever having a psychotic experience being estimated at 5.8% [ 3 ]. However, rates of psychotic symptoms and experiences are disproportionately high amongst LGBTQA+ populations, with non-heterosexual individuals estimated to be 1.99–3.75 times more likely to experience psychosis than their heterosexual peers [ 4 , 5 , 6 , 7 ]. Additionally, it has been estimated that transgender or gender non-conforming (henceforth trans) individuals are 2.46–49.7 times more likely than their cisgender peers (i.e. individuals whose gender identity is the same as their birth registered sex) to receive a psychotic disorder diagnosis [ 8 , 9 ]. The increased rates of psychotic experiences noted amongst gender and sexual minorities may be explained by evidence indicating that LGBTQA+ people are also exposed to risk factors for psychosis at a far greater rate than members of the general population, such as childhood adversity [ 10 , 11 , 12 ], minority stress [ 13 ], discrimination [ 14 ], and stigma [ 15 , 16 ]. Furthermore, there is added potential for diagnostic biases leading to over-diagnosing psychosis in gender diverse individuals, whose gender expression and dysphoria may be pathologized by mental health service providers [ 8 ].

Despite these concerning statistics, there is very little research examining the experiences of LGBTQA+ people with psychosis, and limited consideration of the unique needs these individuals may have in accessing and engaging with mental health services. While timely access to treatment has consistently been associated with better symptomatic and functional outcomes for people with psychosis [ 17 , 18 ], there are often delays to treatment initiation which are worsened for LGBTQA+ individuals [ 19 , 20 ]. These individuals face additional barriers to accessing adequate mental health support compared to cisgender/heterosexual people [ 19 ] and may need to experiment with several mental health services before finding culturally competent care [ 20 ]. This in turn may lead to longer duration of untreated psychosis. Additionally, there seems to be a lack of targeted support for this population from healthcare providers, with LGBTQA+ individuals with serious mental health concerns reporting higher rates of dissatisfaction with psychiatric services than their cisgender and heterosexual counterparts [ 7 , 14 , 21 ]. However, the extent of these differences varies across contexts [ 22 ], potentially due to improved education around stigma and LGBTQA+ issues within a subset of mental health services.

Nonetheless, stigma remains one of the highest cited barriers to help-seeking for mental health problems, particularly with regard to concerns around disclosure [ 23 ], which can be particularly challenging for people experiencing psychosis [ 24 , 25 ]. Stigma stress in young people at risk for psychosis is associated with less positive attitudes towards help-seeking regarding both psychiatric medication and psychotherapy [ 26 ], potentially partly due to fears of judgement and being treated differently by service providers [ 27 ]. This issue may be compounded for people who also belong to minoritized groups [ 23 , 28 ], particularly as LGBTQA+ individuals have reported experiencing frequent stigma and encountering uninformed staff when accessing mental healthcare [ 7 , 29 ]. Furthermore, stigma-fuelled hesitance to access services may be heightened for trans people [ 30 ] whose identities have historically been pathologized and conflated with experiences of psychosis [ 31 ].

Even when individuals manage to overcome barriers to access support, there are added challenges to maintaining adequate treatment engagement. In a large online study, half of trans and nearly one third of LGB participants reported having stopped using mental health services in the past because of negative experiences related to their gender identity or sexuality [ 20 ]. This can be particularly problematic as experiences of stigma predict poorer medication adherence in psychosis [ 32 ] which subsequently multiplies the risk for relapse and suicide [ 33 ]. While no research to date has explored non-adherence rates in people with psychosis who are LGBTQA+, concerns around suicidality are heightened for individuals who are gender and sexuality diverse [ 34 , 35 , 36 ].

Generally, there is rising demand for mental healthcare that specifically addresses the needs of gender and sexual minority individuals and promotes respect for diversity, equity, and inclusion [ 29 , 37 ]. This is particularly salient as positive relationships with staff are associated with better medication adherence for people with psychosis [ 38 ] and healthcare providers with LGBTQA+-specific mandates have demonstrated higher satisfaction rates for LGBTQA+ individuals [ 20 ]. Mental health services need to adapt treatment options to acknowledge minority stress factors for those with stigmatised identities and, perhaps more importantly, how these intersect and interact to increase inequalities in people from minoritized groups accessing and benefiting from treatment [ 37 , 39 ].

Additionally, gender affirming care needs to be recognised as an important facet of mental health treatment for many trans individuals, as it is associated with positive outcomes such as improvements in quality of life and psychological functioning [ 40 , 41 , 42 ] and reductions in psychiatric symptom severity and need for subsequent mental health treatment [ 8 , 43 ]. While there are additional barriers in access to gender affirming care for individuals with psychosis, this treatment has shown success in parallel with treatment to address psychosis symptom stabilisation [ 19 , 44 ]. The importance of affirmation is echoed by the finding that many negative experiences of LGBTQA+ participants with mental health services could be avoided simply by respecting people’s pronouns and using gender-neutral language [ 20 ].

To ensure timely access to appropriate treatment for LGBTQA+ people with psychosis, there is a need for improved understanding of the factors which challenge and facilitate help-seeking and engagement with mental health support. A preliminary search of Google Scholar, Medline, the Cochrane Database of Systematic Reviews, and PROSPERO was conducted and revealed no existing or planned reviews exploring benefits and/or obstacles to mental health treatment specific to this population. Therefore, the proposed review seeks to comprehensively search and appraise the existing literature to identify and summarise a range of barriers and facilitators to adequate mental health support faced by LGBTQA+ people with experiences of psychosis. This will allow for the mapping of the types of evidence available and identification of any knowledge gaps. Moreover, we hope to guide future decision-making in mental healthcare to improve service accessibility for LGBTQA+ individuals with psychosis and to set the foundations for future research that centres this marginalised population. Based on published guidance [ 45 , 46 , 47 ], a scoping review methodology was identified as the most appropriate approach to address these aims.

Selection criteria

This scoping review protocol has been developed in compliance with the JBI Manual for Evidence Synthesis [ 48 ] and, where relevant, the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) checklist [ 49 ] (see Additional file 1). In the event of protocol amendments, the date, justification, and description for each amendment will be provided.

Due to the limited literature around the topic of this review, any primary original study design, setting, and publication date will be considered for inclusion. Publications written in English will be included, and articles in other languages may be considered pending time and cost constraints around translation. Publications will be excluded if the full text is not available upon request from authors.

The PCC (Population, Concept, Context) framework was used to develop the inclusion criteria for this scoping review:

This review will include individuals of any age who are LGBTQA+ and have had experiences of psychosis. For the purposes of this review, ‘LGBTQA+ individuals’ will be broadly defined as any individual that is not heterosexual and/or cisgender or anyone who engages in same-gender sexual behaviour. Studies may include participants who are cisgender and heterosexual if they separately report outcomes for LGBTQA+ individuals. Within this review, the term ‘psychosis’ includes (i) any diagnosis of a psychotic disorder, such as schizophrenia spectrum disorders, mood disorders with psychotic features, delusional disorders, and drug-induced psychotic disorders, (ii) sub-threshold psychotic symptoms, such as those present in ultra-high risk (UHR), clinical high risk (CHR), or at risk mental state (ARMS) individuals, and (iii) any psychotic-like symptoms or experiences. Studies may include participants with multiple diagnoses if they separately report outcomes for individuals on the psychosis spectrum.

This review will include publications which discuss potential barriers and/or facilitators to mental health help-seeking and/or engagement with mental health treatment. ‘Barriers’ will be operationalised as any factors which may delay or prevent individuals from accessing and engaging with appropriate mental health support. These may include lack of mental health education, experienced or internalised stigma, experiences of discrimination from health services, and lack of inclusivity in health services. ‘Facilitators’ will be operationalised as any factors which may promote timely help-seeking and engagement with sources of support. These may include improved access to mental health education, positive sources of social support, and welcoming and inclusive services. Mental health help-seeking will be broadly defined as any attempt to seek and access formal or informal support to address a mental health concern related to experiences of psychosis (e.g. making an initial appointment with a service provider, seeking help from a friend). Mental health treatment engagement will be broadly defined as adherence and active participation in the treatment that is offered by a source of support (e.g. attending scheduled appointments, taking medication as prescribed, openly communicating with service providers).

This review may include research encompassing any setting in which mental healthcare is provided. This is likely to include formal healthcare settings such as community mental health teams or inpatient clinics as well as informal settings such as LGBTQA+ spaces or informal peer support. Studies will be excluded if they focus exclusively on physical health treatment.

Search strategy

Database searches will be conducted in Medline, PsycINFO, Embase, Scopus, and LGBTQ+ Source. The full search strategy for this protocol is available (see Additional file 2). This strategy has been collaboratively developed and evaluated by a scholarly services health librarian. Searches will include subject headings relevant to each database and title/abstract keywords relating to three main concepts: (i) LGBTQA+ identity, (ii) experiences of psychosis, and (iii) mental health treatment. Keywords for each concept will be combined using the Boolean operator ‘OR’, and the three concepts will be combined using ‘AND’. This search strategy was appropriately translated for each of the selected databases. There will be no limitations on language or publication date at this stage to maximise the breadth of the literature captured. Publications returned from these searches will be exported to EndNote. Searches will be re-run prior to the final analysis to capture any newly published studies.

The database searches will be supplemented by searching the grey literature as per the eligibility criteria detailed above. These may include theses and dissertations, conference proceedings, reports from mental health services, and policy documents from LGBTQA+ groups. Google and Google Scholar will be searched using a combination of clauses for psychosis (Psychosis OR psychotic OR schizophrenia OR schizoaffective), treatment (treatment or “help-seeking”), and queer identity. The latter concept will have three clauses for three separate searches, with one including broad queer identity (LGBT), one specific to non-heterosexual individuals (gay OR lesbian OR homosexual OR bisexual OR queer OR asexual), and one specific to trans individuals (transgender OR transsexual OR transexual OR “non-binary” OR “gender minority”). Additionally, reference lists and citing literature will be manually searched for each paper included in the review to capture any articles and policy documents not previously identified.

Data selection

Search results will be imported into Covidence using EndNote, and duplicates will be eliminated. Titles and abstracts will be screened by the first and second authors according to pre-defined screening criteria, which will be discussed by the authors and piloted prior to screening. These criteria will consider whether the articles included LGBTQA+ participants with experiences of psychosis (as operationalised above) in relation to mental health help-seeking and/or treatment. Full texts of relevant articles will then be obtained and screened by the first and second reviewer in accordance with the full inclusion and exclusion criteria after initial piloting to maximise inter-rater reliability. Decisions on inclusion and exclusion will be blinded and recorded on Covidence. Potential discrepancies will be resolved through discussion, and when consensus cannot be reached, these will be resolved by the supervising author. The process of study selection will be documented using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram [ 50 ].

Data extraction

Data extraction will be performed independently by two reviewers using Covidence. Prior to beginning final extraction, both reviewers will independently pilot the extraction tool using a sample of five included studies and discuss any necessary changes. Information extracted is planned to include the following: title, author name(s), year of publication, country in which the study was conducted, study design, sample size, population of focus (i.e. sexual minorities, gender minorities, or both), sample demographics (i.e. age, gender identity, and sexual orientation), setting (e.g. early intervention service, community mental health team, etc.), psychosis characteristics (e.g. diagnoses included, severity of symptoms, etc.), type of treatment (e.g. cognitive behavioural therapy, antipsychotic medication, etc.), and any barriers and/or facilitators identified according to the aforementioned operationalised definitions. Disagreements will be resolved through discussion between the two reviewers and, when necessary, final decisions will be made by a senior supervisor. Once extracted, information will be recorded in Excel. Lead authors of papers will be contacted by the primary review author in cases where there is missing or insufficient data.

Quality assessment

Due to the expected heterogeneity in the types of studies that may be included in this review (e.g. qualitative studies, randomised controlled trials, case control studies, case reports), the relevant revised Joanna Briggs Institute (JBI) critical appraisal checklists [ 51 ] will be used to assess risk of bias and study quality for each study design. Two reviewers will independently use these checklists to assess each paper that is included following the full-text screening. If there are discrepancies in article ratings, these will be resolved through discussion between the two authors. If no consensus is reached, discrepancies will be resolved by a senior supervisor. In line with the scoping nature of this review, low-quality studies will not be excluded from the synthesis.

Evidence synthesis

Data from included studies will be synthesised using a narrative synthesis approach in accordance with the Guidance on the Conduct of Narrative Synthesis in Systematic Reviews [ 52 ]. A preliminary descriptive synthesis will be conducted by tabulating the extracted data elements from each study alongside quality assessment results and developing an initial description of the barriers and facilitators to (1) accessing and (2) engaging with mental health support that are identified in the literature. This initial synthesis will then be interrogated and refined to contextualise these barriers and facilitators in the setting, population, and methodology of each study to form the basis for an interpretative synthesis.

This review will not use a pre-existing thematic framework to categorise barriers and facilitators as it is expected that the factors identified will not neatly fit into existing criteria. Instead, these will be conceptualised according to overarching themes as interrelated factors, so that potentially complex interactions between barriers and facilitators within and across relevant studies may be explored through concept mapping. If most of the studies included are qualitative, there may also be scope for a partial meta-synthesis. To avoid oversimplifying the concept of ‘barriers and facilitators’ (see criticism by Bach-Mortensen & Verboom [ 53 ]), this data synthesis will be followed by a critical reflection of the findings through the lens of the socio-political contexts which may give rise to the barriers and facilitators identified, exploring the complexities necessary for any changes to be implemented in mental health services.

If the extracted data indicate that gender minority and sexual minority individuals experience unique or different barriers and/or facilitators to each other, these population groups will be analysed separately as opposed to findings being generalised across the LGBTQA+ spectrum. Furthermore, if there is scope to do so, analyses may be conducted to investigate how perceived barriers and facilitators for this population may have changed over time (i.e. according to publication date) as definitions of psychosis evolve and LGBTQA+ individuals gain visibility in clinical services.

The proposed review will add to the literature around mental health treatment for LGBTQA+ people with psychosis. It will provide a thorough account of the barriers and facilitators to accessing and engaging with support faced by this population and may inform future research and clinical practice.

In terms of limitations, this review will be constrained by the existing literature and may therefore not be sufficiently comprehensive in reflecting the barriers and facilitators experienced by subgroups within the broader LGBTQA+ community. Additionally, although broad inclusion criteria are necessary to capture the full breadth of research conducted in this topic, included studies are likely to be heterogeneous and varied in terms of their methodology and population which may complicate data synthesis.

Nonetheless, it is anticipated that the findings from this review will provide the most comprehensive synthesis to date of the issues driving low help-seeking and treatment engagement in people across the psychosis spectrum who are LGBTQA+. This review will likely also identify gaps in the literature which may inform avenues for future research, and the factors identified in this review will be considered in subsequent research by the authors.

Additionally, findings will be relevant to healthcare providers that offer support to people with psychosis who may have intersecting LGBTQA+ identities as well as LGBTQA+ organisations which offer support to LGBTQA+ people who may be experiencing distressing psychotic experiences. These services are likely to benefit from an increased awareness of the factors which may improve or hinder accessibility for these subsets of their target populations. Therefore, results from this review may inform decision-making around the implementation of service-wide policy changes.

The findings of this review will be disseminated through the publication of an article in a peer-reviewed journal and presented at relevant conferences in Australia and/or internationally. Additionally, the completed review will form part of the lead author’s doctoral thesis.

Availability of data and materials

Not applicable for this protocol.

Abbreviations

• At risk mental state

Clinical high risk for psychosis

Joanna Briggs Institute

Lesbian, gay, and bisexual

Lesbian, gay, bisexual, transgender, queer or questioning, asexual or aromantic, and more

Population, Concept, Context

Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols

Ultra-high risk for psychosis

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Acknowledgements

The authors would like to acknowledge the support of Ms Olivia Larobina, Scholarly Services Librarian (STEMM) at Deakin University, in the development of the search strategy.

CCG is funded by a Deakin University Postgraduate Research (DUPR) Scholarship. ZW is funded by a University of Western Australia Research Training Program (RTP) Scholarship. AL is supported by a National Health and Medical Research Council (NHMRC) Emerging Leaders Fellowship (2010063). LJW is supported by a NHMRC Emerging Leaders Fellowship (1174060). ARY is supported by a NHMRC Principal Research Fellowship (1136829). The funding providers had no role in the design and conduct of the study, or in the preparation, review, or approval of this manuscript.

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Additional file 1. prisma-p 2015 checklist. completed prisma-p checklist for this systematic review protocol., 13643_2024_2566_moesm2_esm.docx.

Additional file 2. Search Strategy. Detailed search strategy for this systematic review, including search terms and relevant controlled vocabulary terms for each included database.

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Gonçalves, C.C., Waters, Z., Quirk, S.E. et al. Barriers and facilitators to mental health treatment access and engagement for LGBTQA+ people with psychosis: a scoping review protocol. Syst Rev 13 , 143 (2024). https://doi.org/10.1186/s13643-024-02566-5

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Approaching literature review for academic purposes: The Literature Review Checklist

Debora f.b. leite.

I Departamento de Ginecologia e Obstetricia, Faculdade de Ciencias Medicas, Universidade Estadual de Campinas, Campinas, SP, BR

II Universidade Federal de Pernambuco, Pernambuco, PE, BR

III Hospital das Clinicas, Universidade Federal de Pernambuco, Pernambuco, PE, BR

Maria Auxiliadora Soares Padilha

Jose g. cecatti.

A sophisticated literature review (LR) can result in a robust dissertation/thesis by scrutinizing the main problem examined by the academic study; anticipating research hypotheses, methods and results; and maintaining the interest of the audience in how the dissertation/thesis will provide solutions for the current gaps in a particular field. Unfortunately, little guidance is available on elaborating LRs, and writing an LR chapter is not a linear process. An LR translates students’ abilities in information literacy, the language domain, and critical writing. Students in postgraduate programs should be systematically trained in these skills. Therefore, this paper discusses the purposes of LRs in dissertations and theses. Second, the paper considers five steps for developing a review: defining the main topic, searching the literature, analyzing the results, writing the review and reflecting on the writing. Ultimately, this study proposes a twelve-item LR checklist. By clearly stating the desired achievements, this checklist allows Masters and Ph.D. students to continuously assess their own progress in elaborating an LR. Institutions aiming to strengthen students’ necessary skills in critical academic writing should also use this tool.

INTRODUCTION

Writing the literature review (LR) is often viewed as a difficult task that can be a point of writer’s block and procrastination ( 1 ) in postgraduate life. Disagreements on the definitions or classifications of LRs ( 2 ) may confuse students about their purpose and scope, as well as how to perform an LR. Interestingly, at many universities, the LR is still an important element in any academic work, despite the more recent trend of producing scientific articles rather than classical theses.

The LR is not an isolated section of the thesis/dissertation or a copy of the background section of a research proposal. It identifies the state-of-the-art knowledge in a particular field, clarifies information that is already known, elucidates implications of the problem being analyzed, links theory and practice ( 3 - 5 ), highlights gaps in the current literature, and places the dissertation/thesis within the research agenda of that field. Additionally, by writing the LR, postgraduate students will comprehend the structure of the subject and elaborate on their cognitive connections ( 3 ) while analyzing and synthesizing data with increasing maturity.

At the same time, the LR transforms the student and hints at the contents of other chapters for the reader. First, the LR explains the research question; second, it supports the hypothesis, objectives, and methods of the research project; and finally, it facilitates a description of the student’s interpretation of the results and his/her conclusions. For scholars, the LR is an introductory chapter ( 6 ). If it is well written, it demonstrates the student’s understanding of and maturity in a particular topic. A sound and sophisticated LR can indicate a robust dissertation/thesis.

A consensus on the best method to elaborate a dissertation/thesis has not been achieved. The LR can be a distinct chapter or included in different sections; it can be part of the introduction chapter, part of each research topic, or part of each published paper ( 7 ). However, scholars view the LR as an integral part of the main body of an academic work because it is intrinsically connected to other sections ( Figure 1 ) and is frequently present. The structure of the LR depends on the conventions of a particular discipline, the rules of the department, and the student’s and supervisor’s areas of expertise, needs and interests.

Interestingly, many postgraduate students choose to submit their LR to peer-reviewed journals. As LRs are critical evaluations of current knowledge, they are indeed publishable material, even in the form of narrative or systematic reviews. However, systematic reviews have specific patterns 1 ( 8 ) that may not entirely fit with the questions posed in the dissertation/thesis. Additionally, the scope of a systematic review may be too narrow, and the strict criteria for study inclusion may omit important information from the dissertation/thesis. Therefore, this essay discusses the definition of an LR is and methods to develop an LR in the context of an academic dissertation/thesis. Finally, we suggest a checklist to evaluate an LR.

WHAT IS A LITERATURE REVIEW IN A THESIS?

Conducting research and writing a dissertation/thesis translates rational thinking and enthusiasm ( 9 ). While a strong body of literature that instructs students on research methodology, data analysis and writing scientific papers exists, little guidance on performing LRs is available. The LR is a unique opportunity to assess and contrast various arguments and theories, not just summarize them. The research results should not be discussed within the LR, but the postgraduate student tends to write a comprehensive LR while reflecting on his or her own findings ( 10 ).

Many people believe that writing an LR is a lonely and linear process. Supervisors or the institutions assume that the Ph.D. student has mastered the relevant techniques and vocabulary associated with his/her subject and conducts a self-reflection about previously published findings. Indeed, while elaborating the LR, the student should aggregate diverse skills, which mainly rely on his/her own commitment to mastering them. Thus, less supervision should be required ( 11 ). However, the parameters described above might not currently be the case for many students ( 11 , 12 ), and the lack of formal and systematic training on writing LRs is an important concern ( 11 ).

An institutional environment devoted to active learning will provide students the opportunity to continuously reflect on LRs, which will form a dialogue between the postgraduate student and the current literature in a particular field ( 13 ). Postgraduate students will be interpreting studies by other researchers, and, according to Hart (1998) ( 3 ), the outcomes of the LR in a dissertation/thesis include the following:

• To identify what research has been performed and what topics require further investigation in a particular field of knowledge;
• To determine the context of the problem;
• To recognize the main methodologies and techniques that have been used in the past;
• To place the current research project within the historical, methodological and theoretical context of a particular field;
• To identify significant aspects of the topic;
• To elucidate the implications of the topic;
• To offer an alternative perspective;
• To discern how the studied subject is structured;
• To improve the student’s subject vocabulary in a particular field; and
• To characterize the links between theory and practice.

A sound LR translates the postgraduate student’s expertise in academic and scientific writing: it expresses his/her level of comfort with synthesizing ideas ( 11 ). The LR reveals how well the postgraduate student has proceeded in three domains: an effective literature search, the language domain, and critical writing.

Effective literature search

All students should be trained in gathering appropriate data for specific purposes, and information literacy skills are a cornerstone. These skills are defined as “an individual’s ability to know when they need information, to identify information that can help them address the issue or problem at hand, and to locate, evaluate, and use that information effectively” ( 14 ). Librarian support is of vital importance in coaching the appropriate use of Boolean logic (AND, OR, NOT) and other tools for highly efficient literature searches (e.g., quotation marks and truncation), as is the appropriate management of electronic databases.

Language domain

Academic writing must be concise and precise: unnecessary words distract the reader from the essential content ( 15 ). In this context, reading about issues distant from the research topic ( 16 ) may increase students’ general vocabulary and familiarity with grammar. Ultimately, reading diverse materials facilitates and encourages the writing process itself.

Critical writing

Critical judgment includes critical reading, thinking and writing. It supposes a student’s analytical reflection about what he/she has read. The student should delineate the basic elements of the topic, characterize the most relevant claims, identify relationships, and finally contrast those relationships ( 17 ). Each scientific document highlights the perspective of the author, and students will become more confident in judging the supporting evidence and underlying premises of a study and constructing their own counterargument as they read more articles. A paucity of integration or contradictory perspectives indicates lower levels of cognitive complexity ( 12 ).

Thus, while elaborating an LR, the postgraduate student should achieve the highest category of Bloom’s cognitive skills: evaluation ( 12 ). The writer should not only summarize data and understand each topic but also be able to make judgments based on objective criteria, compare resources and findings, identify discrepancies due to methodology, and construct his/her own argument ( 12 ). As a result, the student will be sufficiently confident to show his/her own voice .

Writing a consistent LR is an intense and complex activity that reveals the training and long-lasting academic skills of a writer. It is not a lonely or linear process. However, students are unlikely to be prepared to write an LR if they have not mastered the aforementioned domains ( 10 ). An institutional environment that supports student learning is crucial.

Different institutions employ distinct methods to promote students’ learning processes. First, many universities propose modules to develop behind the scenes activities that enhance self-reflection about general skills (e.g., the skills we have mastered and the skills we need to develop further), behaviors that should be incorporated (e.g., self-criticism about one’s own thoughts), and each student’s role in the advancement of his/her field. Lectures or workshops about LRs themselves are useful because they describe the purposes of the LR and how it fits into the whole picture of a student’s work. These activities may explain what type of discussion an LR must involve, the importance of defining the correct scope, the reasons to include a particular resource, and the main role of critical reading.

Some pedagogic services that promote a continuous improvement in study and academic skills are equally important. Examples include workshops about time management, the accomplishment of personal objectives, active learning, and foreign languages for nonnative speakers. Additionally, opportunities to converse with other students promotes an awareness of others’ experiences and difficulties. Ultimately, the supervisor’s role in providing feedback and setting deadlines is crucial in developing students’ abilities and in strengthening students’ writing quality ( 12 ).

HOW SHOULD A LITERATURE REVIEW BE DEVELOPED?

A consensus on the appropriate method for elaborating an LR is not available, but four main steps are generally accepted: defining the main topic, searching the literature, analyzing the results, and writing ( 6 ). We suggest a fifth step: reflecting on the information that has been written in previous publications ( Figure 2 ).

First step: Defining the main topic

Planning an LR is directly linked to the research main question of the thesis and occurs in parallel to students’ training in the three domains discussed above. The planning stage helps organize ideas, delimit the scope of the LR ( 11 ), and avoid the wasting of time in the process. Planning includes the following steps:

• Reflecting on the scope of the LR: postgraduate students will have assumptions about what material must be addressed and what information is not essential to an LR ( 13 , 18 ). Cooper’s Taxonomy of Literature Reviews 2 systematizes the writing process through six characteristics and nonmutually exclusive categories. The focus refers to the reviewer’s most important points of interest, while the goals concern what students want to achieve with the LR. The perspective assumes answers to the student’s own view of the LR and how he/she presents a particular issue. The coverage defines how comprehensive the student is in presenting the literature, and the organization determines the sequence of arguments. The audience is defined as the group for whom the LR is written.
• Designating sections and subsections: Headings and subheadings should be specific, explanatory and have a coherent sequence throughout the text ( 4 ). They simulate an inverted pyramid, with an increasing level of reflection and depth of argument.
• Identifying keywords: The relevant keywords for each LR section should be listed to guide the literature search. This list should mirror what Hart (1998) ( 3 ) advocates as subject vocabulary . The keywords will also be useful when the student is writing the LR since they guide the reader through the text.
• Delineating the time interval and language of documents to be retrieved in the second step. The most recently published documents should be considered, but relevant texts published before a predefined cutoff year can be included if they are classic documents in that field. Extra care should be employed when translating documents.

Second step: Searching the literature

The ability to gather adequate information from the literature must be addressed in postgraduate programs. Librarian support is important, particularly for accessing difficult texts. This step comprises the following components:

• Searching the literature itself: This process consists of defining which databases (electronic or dissertation/thesis repositories), official documents, and books will be searched and then actively conducting the search. Information literacy skills have a central role in this stage. While searching electronic databases, controlled vocabulary (e.g., Medical Subject Headings, or MeSH, for the PubMed database) or specific standardized syntax rules may need to be applied.

In addition, two other approaches are suggested. First, a review of the reference list of each document might be useful for identifying relevant publications to be included and important opinions to be assessed. This step is also relevant for referencing the original studies and leading authors in that field. Moreover, students can directly contact the experts on a particular topic to consult with them regarding their experience or use them as a source of additional unpublished documents.

Before submitting a dissertation/thesis, the electronic search strategy should be repeated. This process will ensure that the most recently published papers will be considered in the LR.

• Selecting documents for inclusion: Generally, the most recent literature will be included in the form of published peer-reviewed papers. Assess books and unpublished material, such as conference abstracts, academic texts and government reports, are also important to assess since the gray literature also offers valuable information. However, since these materials are not peer-reviewed, we recommend that they are carefully added to the LR.

This task is an important exercise in time management. First, students should read the title and abstract to understand whether that document suits their purposes, addresses the research question, and helps develop the topic of interest. Then, they should scan the full text, determine how it is structured, group it with similar documents, and verify whether other arguments might be considered ( 5 ).

Third step: Analyzing the results

Critical reading and thinking skills are important in this step. This step consists of the following components:

• Reading documents: The student may read various texts in depth according to LR sections and subsections ( defining the main topic ), which is not a passive activity ( 1 ). Some questions should be asked to practice critical analysis skills, as listed below. Is the research question evident and articulated with previous knowledge? What are the authors’ research goals and theoretical orientations, and how do they interact? Are the authors’ claims related to other scholars’ research? Do the authors consider different perspectives? Was the research project designed and conducted properly? Are the results and discussion plausible, and are they consistent with the research objectives and methodology? What are the strengths and limitations of this work? How do the authors support their findings? How does this work contribute to the current research topic? ( 1 , 19 )
• Taking notes: Students who systematically take notes on each document are more readily able to establish similarities or differences with other documents and to highlight personal observations. This approach reinforces the student’s ideas about the next step and helps develop his/her own academic voice ( 1 , 13 ). Voice recognition software ( 16 ), mind maps ( 5 ), flowcharts, tables, spreadsheets, personal comments on the referenced texts, and note-taking apps are all available tools for managing these observations, and the student him/herself should use the tool that best improves his/her learning. Additionally, when a student is considering submitting an LR to a peer-reviewed journal, notes should be taken on the activities performed in all five steps to ensure that they are able to be replicated.

Fourth step: Writing

The recognition of when a student is able and ready to write after a sufficient period of reading and thinking is likely a difficult task. Some students can produce a review in a single long work session. However, as discussed above, writing is not a linear process, and students do not need to write LRs according to a specific sequence of sections. Writing an LR is a time-consuming task, and some scholars believe that a period of at least six months is sufficient ( 6 ). An LR, and academic writing in general, expresses the writer’s proper thoughts, conclusions about others’ work ( 6 , 10 , 13 , 16 ), and decisions about methods to progress in the chosen field of knowledge. Thus, each student is expected to present a different learning and writing trajectory.

In this step, writing methods should be considered; then, editing, citing and correct referencing should complete this stage, at least temporarily. Freewriting techniques may be a good starting point for brainstorming ideas and improving the understanding of the information that has been read ( 1 ). Students should consider the following parameters when creating an agenda for writing the LR: two-hour writing blocks (at minimum), with prespecified tasks that are possible to complete in one section; short (minutes) and long breaks (days or weeks) to allow sufficient time for mental rest and reflection; and short- and long-term goals to motivate the writing itself ( 20 ). With increasing experience, this scheme can vary widely, and it is not a straightforward rule. Importantly, each discipline has a different way of writing ( 1 ), and each department has its own preferred styles for citations and references.

Fifth step: Reflecting on the writing

In this step, the postgraduate student should ask him/herself the same questions as in the analyzing the results step, which can take more time than anticipated. Ambiguities, repeated ideas, and a lack of coherence may not be noted when the student is immersed in the writing task for long periods. The whole effort will likely be a work in progress, and continuous refinements in the written material will occur once the writing process has begun.

LITERATURE REVIEW CHECKLIST

In contrast to review papers, the LR of a dissertation/thesis should not be a standalone piece or work. Instead, it should present the student as a scholar and should maintain the interest of the audience in how that dissertation/thesis will provide solutions for the current gaps in a particular field.

A checklist for evaluating an LR is convenient for students’ continuous academic development and research transparency: it clearly states the desired achievements for the LR of a dissertation/thesis. Here, we present an LR checklist developed from an LR scoring rubric ( 11 ). For a critical analysis of an LR, we maintain the five categories but offer twelve criteria that are not scaled ( Figure 3 ). The criteria all have the same importance and are not mutually exclusive.

First category: Coverage

1. justified criteria exist for the inclusion and exclusion of literature in the review.

This criterion builds on the main topic and areas covered by the LR ( 18 ). While experts may be confident in retrieving and selecting literature, postgraduate students must convince their audience about the adequacy of their search strategy and their reasons for intentionally selecting what material to cover ( 11 ). References from different fields of knowledge provide distinct perspective, but narrowing the scope of coverage may be important in areas with a large body of existing knowledge.

Second category: Synthesis

2. a critical examination of the state of the field exists.

A critical examination is an assessment of distinct aspects in the field ( 1 ) along with a constructive argument. It is not a negative critique but an expression of the student’s understanding of how other scholars have added to the topic ( 1 ), and the student should analyze and contextualize contradictory statements. A writer’s personal bias (beliefs or political involvement) have been shown to influence the structure and writing of a document; therefore, the cultural and paradigmatic background guide how the theories are revised and presented ( 13 ). However, an honest judgment is important when considering different perspectives.

3. The topic or problem is clearly placed in the context of the broader scholarly literature

The broader scholarly literature should be related to the chosen main topic for the LR ( how to develop the literature review section). The LR can cover the literature from one or more disciplines, depending on its scope, but it should always offer a new perspective. In addition, students should be careful in citing and referencing previous publications. As a rule, original studies and primary references should generally be included. Systematic and narrative reviews present summarized data, and it may be important to cite them, particularly for issues that should be understood but do not require a detailed description. Similarly, quotations highlight the exact statement from another publication. However, excessive referencing may disclose lower levels of analysis and synthesis by the student.

4. The LR is critically placed in the historical context of the field

Situating the LR in its historical context shows the level of comfort of the student in addressing a particular topic. Instead of only presenting statements and theories in a temporal approach, which occasionally follows a linear timeline, the LR should authentically characterize the student’s academic work in the state-of-art techniques in their particular field of knowledge. Thus, the LR should reinforce why the dissertation/thesis represents original work in the chosen research field.

5. Ambiguities in definitions are considered and resolved

Distinct theories on the same topic may exist in different disciplines, and one discipline may consider multiple concepts to explain one topic. These misunderstandings should be addressed and contemplated. The LR should not synthesize all theories or concepts at the same time. Although this approach might demonstrate in-depth reading on a particular topic, it can reveal a student’s inability to comprehend and synthesize his/her research problem.

6. Important variables and phenomena relevant to the topic are articulated

The LR is a unique opportunity to articulate ideas and arguments and to purpose new relationships between them ( 10 , 11 ). More importantly, a sound LR will outline to the audience how these important variables and phenomena will be addressed in the current academic work. Indeed, the LR should build a bidirectional link with the remaining sections and ground the connections between all of the sections ( Figure 1 ).

7. A synthesized new perspective on the literature has been established

The LR is a ‘creative inquiry’ ( 13 ) in which the student elaborates his/her own discourse, builds on previous knowledge in the field, and describes his/her own perspective while interpreting others’ work ( 13 , 17 ). Thus, students should articulate the current knowledge, not accept the results at face value ( 11 , 13 , 17 ), and improve their own cognitive abilities ( 12 ).

Third category: Methodology

8. the main methodologies and research techniques that have been used in the field are identified and their advantages and disadvantages are discussed.

The LR is expected to distinguish the research that has been completed from investigations that remain to be performed, address the benefits and limitations of the main methods applied to date, and consider the strategies for addressing the expected limitations described above. While placing his/her research within the methodological context of a particular topic, the LR will justify the methodology of the study and substantiate the student’s interpretations.

9. Ideas and theories in the field are related to research methodologies

The audience expects the writer to analyze and synthesize methodological approaches in the field. The findings should be explained according to the strengths and limitations of previous research methods, and students must avoid interpretations that are not supported by the analyzed literature. This criterion translates to the student’s comprehension of the applicability and types of answers provided by different research methodologies, even those using a quantitative or qualitative research approach.

Fourth category: Significance

10. the scholarly significance of the research problem is rationalized.

The LR is an introductory section of a dissertation/thesis and will present the postgraduate student as a scholar in a particular field ( 11 ). Therefore, the LR should discuss how the research problem is currently addressed in the discipline being investigated or in different disciplines, depending on the scope of the LR. The LR explains the academic paradigms in the topic of interest ( 13 ) and methods to advance the field from these starting points. However, an excess number of personal citations—whether referencing the student’s research or studies by his/her research team—may reflect a narrow literature search and a lack of comprehensive synthesis of ideas and arguments.

11. The practical significance of the research problem is rationalized

The practical significance indicates a student’s comprehensive understanding of research terminology (e.g., risk versus associated factor), methodology (e.g., efficacy versus effectiveness) and plausible interpretations in the context of the field. Notably, the academic argument about a topic may not always reflect the debate in real life terms. For example, using a quantitative approach in epidemiology, statistically significant differences between groups do not explain all of the factors involved in a particular problem ( 21 ). Therefore, excessive faith in p -values may reflect lower levels of critical evaluation of the context and implications of a research problem by the student.

Fifth category: Rhetoric

12. the lr was written with a coherent, clear structure that supported the review.

This category strictly relates to the language domain: the text should be coherent and presented in a logical sequence, regardless of which organizational ( 18 ) approach is chosen. The beginning of each section/subsection should state what themes will be addressed, paragraphs should be carefully linked to each other ( 10 ), and the first sentence of each paragraph should generally summarize the content. Additionally, the student’s statements are clear, sound, and linked to other scholars’ works, and precise and concise language that follows standardized writing conventions (e.g., in terms of active/passive voice and verb tenses) is used. Attention to grammar, such as orthography and punctuation, indicates prudence and supports a robust dissertation/thesis. Ultimately, all of these strategies provide fluency and consistency for the text.

Although the scoring rubric was initially proposed for postgraduate programs in education research, we are convinced that this checklist is a valuable tool for all academic areas. It enables the monitoring of students’ learning curves and a concentrated effort on any criteria that are not yet achieved. For institutions, the checklist is a guide to support supervisors’ feedback, improve students’ writing skills, and highlight the learning goals of each program. These criteria do not form a linear sequence, but ideally, all twelve achievements should be perceived in the LR.

CONCLUSIONS

A single correct method to classify, evaluate and guide the elaboration of an LR has not been established. In this essay, we have suggested directions for planning, structuring and critically evaluating an LR. The planning of the scope of an LR and approaches to complete it is a valuable effort, and the five steps represent a rational starting point. An institutional environment devoted to active learning will support students in continuously reflecting on LRs, which will form a dialogue between the writer and the current literature in a particular field ( 13 ).

The completion of an LR is a challenging and necessary process for understanding one’s own field of expertise. Knowledge is always transitory, but our responsibility as scholars is to provide a critical contribution to our field, allowing others to think through our work. Good researchers are grounded in sophisticated LRs, which reveal a writer’s training and long-lasting academic skills. We recommend using the LR checklist as a tool for strengthening the skills necessary for critical academic writing.

AUTHOR CONTRIBUTIONS

Leite DFB has initially conceived the idea and has written the first draft of this review. Padilha MAS and Cecatti JG have supervised data interpretation and critically reviewed the manuscript. All authors have read the draft and agreed with this submission. Authors are responsible for all aspects of this academic piece.

ACKNOWLEDGMENTS

We are grateful to all of the professors of the ‘Getting Started with Graduate Research and Generic Skills’ module at University College Cork, Cork, Ireland, for suggesting and supporting this article. Funding: DFBL has granted scholarship from Brazilian Federal Agency for Support and Evaluation of Graduate Education (CAPES) to take part of her Ph.D. studies in Ireland (process number 88881.134512/2016-01). There is no participation from sponsors on authors’ decision to write or to submit this manuscript.

No potential conflict of interest was reported.

1 The questions posed in systematic reviews usually follow the ‘PICOS’ acronym: Population, Intervention, Comparison, Outcomes, Study design.

2 In 1988, Cooper proposed a taxonomy that aims to facilitate students’ and institutions’ understanding of literature reviews. Six characteristics with specific categories are briefly described: Focus: research outcomes, research methodologies, theories, or practices and applications; Goals: integration (generalization, conflict resolution, and linguistic bridge-building), criticism, or identification of central issues; Perspective: neutral representation or espousal of a position; Coverage: exhaustive, exhaustive with selective citations, representative, central or pivotal; Organization: historical, conceptual, or methodological; and Audience: specialized scholars, general scholars, practitioners or policymakers, or the general public.

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• Victorian Studies

Literature and Medicine: The Nineteenth Century ed. by Clark Lawlor and Andrew Mangham (review)

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• Indiana University Press
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Surgical intervention of Lemierre’s syndrome: a case report and review of the literature

• Yiqi Pan 1   na1 ,
• Zhihong Shi 1   na1 ,
• Qian Da 2 ,
• Chaofu Wang 2 ,
• Yilin Shen 1 &
• Mingliang Xiang   ORCID: orcid.org/0000-0001-9253-9852 1  

Journal of Medical Case Reports volume  18 , Article number:  265 ( 2024 ) Cite this article

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Lemierre’s syndrome is a fatal and rare disease that is typically characterized by oropharyngeal infection and internal jugular vein thrombosis. Timely institution of appropriate antibiotics is the standard treatment.

Case presentation

The authors report a case of Lemierre’s syndrome. A 67-year-old male patient of Han ethnicity in China suffered from a large inflammatory neck mass involving left internal jugular vein thrombosis diagnosed as Lemierre’s syndrome and finally cured by surgical treatment. In addition, a literature review was carried out through PubMed using the terms “Lemierre’s syndrome/disease and review, meta-analysis or retrospective study” and “Lemierre’s syndrome/disease and internal jugular vein”. This search yielded six articles that recorded surgical methods such as drainage, craniotomy, tooth extraction, and ligation of the occluded vein to give clinicians more ideas about the treatment of the Lemierre’s syndrome.

This is the first review to summarize the conditions under which surgical treatment are conducted. Additionally, this is the first report of such a large inflammatory neck mass that was completely cured by surgical resection and internal jugular vein ligation. The authors also offer several conclusions regarding surgical intervention in Lemierre’s syndrome for the first time.

Peer Review reports

Internal jugular vein (IJV) thrombosis is a relatively rare and urgent disease. In a retrospective study, the number of such cases occurring from 2001 to 2008 was 2.5 times that occurring from 1991 to 2000 and 20 times that occurring from 1980 to 1990 [ 1 ]. The reasons behind the increasing incidence of IJV thrombosis include the increase in antibiotic resistance, widespread use of hemodialysis, general application of central venous catheters, expansion of assisted reproductive technology, and increasing incidence of cancer [ 2 ]. In a 9-year retrospective study of 1948 patients with deep vein thrombosis, only 29 patients developed IJV thrombosis, of whom 23 had IJV thrombosis secondary to another condition, such as a malignancy (for example, Trousseau syndrome), central venous catheter implantation, or ovarian hyperstimulation syndrome (OHSS) [ 3 ]. In addition, bilateral internal jugular vein thrombosis is an important indicator of malignant tumors. In a 5-year retrospective study of 41 patients with IJV thrombosis in Germany, paraneoplastic thrombosis accounted for 54% of cases; of these cases, otolaryngology head and neck diseases accounted for 68%. The other patients mostly had inflammatory diseases [ 4 ].

In the ear, nose, and throat (ENT) field, IJV thrombosis is commonly associated with Lemierre’s syndrome (LS), which is a complication of infectious diseases, such as otitis media and oropharyngeal abscess or infection. LS is commonly defined by the following diagnostic criteria: (1) oropharyngeal infection; (2) internal jugular vein thrombophlebitis or thrombosis; (3) septic emboli at a remote site, more frequently the lungs; and (4) isolation of Fusobacterium nucleatum on blood culture [ 5 ]. LS is usually accompanied by septic emboli in the lungs or other organs [ 6 ]. Under some rare conditions, LS can also be triggered by tooth extraction [ 7 ]. Pulmonary embolism, with an incidence of approximately 10%, and postthrombotic syndromes, such as limb pain, heaviness, venous dilatation, edema, pigmentation, nutritional skin changes, and venous ulcers, are complications of IJV thrombosis [ 4 ]. Therefore, ENT doctors should give enough attention to patients with IJV thrombosis to avoid the disastrous results caused by pulmonary or cerebral thrombosis.

To the best of our knowledge, this is the first case of such a large infectious neck mass with internal jugular vein thrombosis that was completely cured by surgical intervention.

A 67-year-old Chinese male of Han ethnicity developed pain in the left neck 14 days prior after eating mud fish. He was healthy and denied a history of infectious diseases, chronic diseases, thrombotic disease, surgical trauma, blood transfusion, allergies, or contact with poisonous substances. Physical examination on admission revealed the following: fever, chills, fatigue, mild dysuria, diffusive swelling pain of the neck on the left side, and high skin temperature. His left neck was tender and edematous with cellulitis. The mass was scleroid with a liquefied center. Other parameters were as follows: white blood cell (WBC) count, 12.2 × 10 9 /L; neutrophil count, 11.76 × 10 9 /L; platelet (PLT) count, 51 × 10 9 /L; C-reactive protein (CRP) level, 146 mg/L; procalcitonin (PCT), 156.99 ng/mL; temperature, 39.5 °C; respiratory rate, 24 breaths per minute; pulse, 118 beats per minute; and blood pressure (BP), 109/61 mmHg. The patient stated that he had been to many hospitals in the last 2 weeks and that the use of antibiotics such as ceftriaxone and metronidazole slightly alleviated his neck pain at first. However, the effect was temporary and no longer present after he transferred to Shanghai, and 3 days before he presented to our hospital, he noticed extreme swelling and felt increased pain in the area of his neck mass (Fig.  1 ). A series of further examinations were performed, with the following results: glucose, 22.13 mmol/L; activated partial thromboplastin time (APTT), 43.1 seconds; prothrombin time (PT), 17.3 seconds; fibrinogen (Fg), 5.0 g/L; fibrin/fibrinogen degradation products (FDP), 7.3 mg/L; and D-dimer (D-D), 2.1 mg/L. Urine analysis was positive for glucose, blood, protein, and white blood cells. Infectious diseases and acute nephrology were considered. The culture of blood and fluid obtained from the mass was negative for any bacteria including anaerobic bacteria, mycoplasma, or fungus. Ultrasound revealed mixed echogenicity in the left neck mass that was irregular in shape. The mass was approximately 74 × 37 mm in size. Color Doppler revealed generalized thrombosis of the internal jugular vein. CT of the chest and neck was conducted and suggested that the cervical abscess extended to the thorax and superior mediastinum, without a signal from the left internal jugular vein. Multiple enlarged cervical lymph nodes were observed. The trachea and left thyroid were also compressed (Fig.  2 ). Video laryngoscopy excluded the possibility of pyriform sinus fistula or any foreign body. Pus obtained from the mass showed many neutrophils and large amounts of necrotic tissue, and 14 days of combination antibiotic treatment (imipenem and teicoplanin) and regular insulin therapy in our hospital returned the patient’s temperature, routine blood markers, CRP and PCT levels, and coagulation function to normal. However, the neck mass remained. Therefore, the surgery department was consulted.

Picture of the patient’s neck showed a huge mass with tenderness (red circles)

A Coronal plane of computed tomography showed neck mass spread down to superior mediastinum with iquefactive necrosis in the center (red arrows). Trachea was oppressed to the right side. B Significant intraluminal filling defect and thrombosis was found in internal jugular vein (yellow arrow)

The patient was taken to the operating room. The neck mass adhered tightly to the surrounding tissue, and the involved segment of the left internal jugular vein was exposed by sharp dissection (Fig.  3 A). The proximal part of the mass needed to be ligated first to avoid small thrombus detachment. There was a large amount of inflammation and fibrosis present in the involved area. The involved segment of the internal jugular vein and the whole neck mass were completely resected, and the distal part of the internal jugular vein was fully ligated (Fig.  3 B). The pathological examination showed hemorrhagic necrosis with the proliferation of fibrous and granulation tissue and the accumulation of foam-like cells and multinuclear giant cells (Fig.  4 ). The patient recovered and was discharged a week after surgery. No other adverse events happened.

Intraoperative view showed ligation of internal jugular vein and separation of the mass ( A ). The resected neck mass as well as left internal jugular vein was shown. Intraluminal thrombosis could be seen clearly when opening the internal jugular vein ( B )

Representative pathological photomicrograph demonstrated thrombus ( A ) and abscess formation ( B )

Literature review

It is rare that patients with Lemierre’s syndrome require surgical intervention when antibiotics and anticoagulant therapies fail. This is the first study to summarize cases of LS requiring surgical treatment (not including abscess drainage). First, we decided to collect previous reviews and meta-analyses to obtain good knowledge of the rate of surgery in LS. Search strategy and selection criteria were as follows. A search of the literature in MEDLINE was performed through PubMed to identify relevant English language articles from 1980 to 2022. The following search terms were used: “Lemierre’s syndrome/disease and review, meta-analysis or retrospective study” and “Lemierre’s syndrome/disease and internal jugular vein”. The references of the retrieved articles were also reviewed to identify additional sources. Through reading the abstract and the full text, we found a total of six reviews and meta-analyses (Table  1 ) that included detailed descriptions of patients who underwent surgery (not including abscess drainage). In a retrospective review from 1998 to 2010 at a local tertiary referral hospital, 17 of the 23 patients underwent surgical treatment of the primary infection site [ 8 ]. In a 5-year systematic review, surgical procedures, such as tooth extraction, craniotomy, and ligation of the occluded vein, were performed in five patients to prevent further septic emboli [ 9 ]. A retrospective study from June 2000 to May 2016 showed that IJV ligation was performed in only one of five LS cases at the Children’s Hospital of Alabama [ 10 ]. In an 8-year Swedish nationwide retrospective study, three patients with peritonsillitis were surgically treated by tonsillectomy [ 11 ]. In the latest meta-analysis of 394 patients in 2020, only 10 patients underwent IJV ligation/excision, only 1 patient underwent ligation/excision of the thrombosed external carotid artery, 3 underwent endoscopic sinus surgery, and 11 underwent mastoidectomy [ 12 ]. In the latest systematic review, which included the most LS cases reported, surgical procedures were performed in 101 patients, and 31 patients underwent IJV ligation/embolectomy [ 13 ].

In this study, we report a case of Lemierre’s syndrome in an elderly male caused by an acute infectious neck mass. Timely comprehensive medical and surgical treatments were given to avoid serious complications.

Internal jugular vein thrombosis is a rare and serious emergent disease that needs to be identified early in the course, as it can lead to catastrophic consequences, such as stroke or pulmonary embolism. The main pathological basis of internal jugular vein thrombosis is as follows: (1) injury of venous intima; (2) slowing down of blood flow; and (3) hypercoagulability. The common causes are as follows [ 14 , 15 , 16 ]: (1) facial infection, such as furuncle and carbuncle, sinusitis, otitis media, and suppurative tonsillitis; bacteria can spread through the damaged mucosa and parapharyngeal space or invade the jugular vein through the lymphatic and venous systems, leading to infectious phlebitis and bacterial embolism information; (2) long duration of internal jugular vein catheterization; (3) head and neck surgery; (4) head and neck tumor; (5) pulmonary embolism; and (6) other systemic diseases, such as polycythemia. Doctors need to take care of patients immediately when encountering such cases.

Lemierre’s syndrome can show the typical symptoms and signs of progressive infection, including sore throat, fever, or neck pain. A systematic review of Lemierre’s syndrome by Peter et al . found that in 84 patients, the most common first clinical presentation was a sore throat (33%), followed by a neck mass (23%) and neck pain (20%) [ 1 ]. In the current case, the patient presented with fever and neck pain at first, followed by a neck mass. The use of antibiotics before he was transferred to our hospital was ineffective. The white blood cell count, PCT level, and erythrocyte sedimentation rate (ESR) were elevated, and blood appeared in his urine. We adjusted the treatment to the combined application of broad-spectrum antibiotics, including imipenem and teicoplanin, for another 2 weeks. The patient’s body temperature returned to normal and laboratory testing showed that the patient’s infectious condition had been controlled, but the neck mass and internal jugular vein thrombosis persisted and required surgical treatment.

Fusobacterium necrophorum is the main pathogen of Lemierre’s syndrome [ 1 ]. However, in this case, the culture of both blood and fluid obtained from the mass was negative for bacteria, which might be because the patient had been treated with antibiotics (mainly including ceftriaxone and metronidazole) for nearly 2 weeks before coming to our hospital. This also suggests that it is particularly important for doctors to culture blood or fluid from the mass before any use of antibiotics in these patients. In many reviews, a large proportion of the cases also did not report any microbiological agent [ 9 , 12 , 13 ] and thus far a clinical diagnosis of LS is still valid if the bacteria go undetected. As for the reason about how this patient got such infectious disease, considering that he had eaten mud fish before the onset of disease and CT showed that mucous of left pyriform sinus was edematous and enhanced (Fig.  5 ), we considered that neck infection might be secondary to the infection of mucous scratch in left pyriform sinus, and uncontrolled hyperglycemia was an important factor to cause serious infection.

Coronal plane of computed tomography showed disappearance of left pyriform sinus surrounding by abnormal enhancement (yellow arrow)

The diagnosis of internal jugular vein thrombosis in Lemierre’s syndrome relies on imaging examination. Ultrasound is the first choice for the diagnosis of LS, and CT and magnetic resonance imaging (MRI) are currently implemented in general practice when necessary. Albertyn et al . first summarized the classic imaging features of internal jugular vein thrombosis. Ultrasonography shows the vein to be distended and nonpulsatile, with internal echoes. CT shows swelling of the adjacent soft tissues, distension of the vein with wall enhancement, and low-attenuation intraluminal filling defects. However, ultrasound has limitations and cannot display the anatomy behind the clavicle or mandible [ 16 ]. In this case, we found that although US can clearly show internal jugular vein thrombosis, knowing its boundaries and connection with the tumor still depends on CT or MRI, especially when there is an urgent need for surgery. A full assessment by preoperative imaging is of great importance. This is also consistent with the views of Charles et al . [ 17 ].

Priority treatment for LS includes antibiotic therapy and drainage of the infected site. Here in our hospital, considering that cephalosporins such as ceftriaxone did not control the fever and pain in this patient, imipenem and teicoplanin were used according to experience to cover wide varieties of Gram-negative and Gram-positive bacteria, including both anaerobic and aerobic bacteria. In addition, teicoplanin has lower side effects than vancomycin [ 18 ]. Rarely, other surgical procedures, such as ligation of the occluded vein, craniotomy, and tooth extraction, are performed. Antithrombotic therapy, including novel oral anticoagulants (DOACs), is also recommended depending on the individual’s condition. However, it remains controversial whether anticoagulation or antithrombotics are effective in Lemierre’s syndrome. Some scholars think that thrombosis is due to the infection process and can be resolved when the infection has been controlled [ 19 ]. In this case, we did not immediately apply anticoagulant or thrombolytic therapies considering that the APTT of this patient was significantly prolonged at the time he came to our hospital and the consumption of platelets was relatively high; emergency anticoagulant therapy may have increased his risk of bleeding. To date, there have been no sufficient clinical studies and no sufficient evidence suggesting the necessity for anticoagulant therapy in Lemierre’s syndrome [ 20 ]. Previous studies have also reported the occurrence of extensive suppurative thrombophlebitis of the bilateral IJV and superior vena cava in patients with Lemierre’s syndrome despite the use of antibiotics and anticoagulant therapy; adjunctive catheter-directed thrombolysis and superior vena cava stenting were performed to help these patients completely recover [ 21 ]. Anticoagulation therapy has not been shown to reduce the complications of Lemierre’s syndrome, such as sepsis [ 17 ]. Meanwhile, Johannesen et al . did not find that anticoagulation therapy decreased the mortality rate or course of the disease or reduced the duration of antibiotic use [ 9 ]. However, anticoagulation therapy is recommended in patients with a poor clinical response despite antibiotic therapy and with a high risk of intracranial thrombosis or recurrent thrombophlebitis [ 22 , 23 , 24 ]. In this case, the cause of internal jugular vein thrombosis was largely infection, so surgical treatment was the best choice when antibiotics could not completely cure the infection and thrombosis. Through previous retrospective studies, systematic reviews and meta-analyses obtained by database searches, we summarized the following points regarding surgical intervention in Lemierre’s syndrome:

When patients do not respond to conservative medical therapy and continue to show extensive septic thrombosis or uncontrolled severe sepsis, surgical treatments need to be considered.

Abscess drainage is the most common and convenient surgical treatment for abscesses upon formation.

Surgical treatment of the primary infection site is effective for controlling the spread of infection and sepsis.

IJV ligation or excision is suitable for patients with persistent septic embolization after treatment with antibiotics and anticoagulants.

IJV ligation or excision is also appropriate to avoid thrombus detachment when anticoagulation therapy or catheter-directed thrombolysis is ineffective.

Lemierre’s syndrome is an extremely rare disease, but the fatality rate can reach 15%, even with escalating antibiotic therapy [ 21 ] . Therefore, early diagnosis is particularly important, and the timely institution of appropriate antibiotics is the standard treatment. Surgical intervention may be the only effective option for controlling the source of infection or when conservative medical treatment fails.

Availability of data and materials

Available from corresponding author on reasonable request.

Abbreviations

Internal jugular vein

Ear, nose, and throat

• Lemierre’s syndrome

White blood cell

C-reactive protein

Procalcitonin

Blood pressure

Computed tomography

Magnetic resonance imaging

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Acknowledgements

Not applicable.

This study was supported by the National Natural Science Foundation of China (grant nos. 82101212, 82101209, 82301296, 82301297), Science and Technology Commission of Shanghai Municipality (grant nos. 23ZR1440200, 21ZR1440200, SHDC2020CR1044B-003), Shanghai “Rising Stars of Medical Talents” Youth Development Program, and Shanghai Municipal Hospital ENT Specialist Alliance.

Author information

Yiqi Pan and Zhihong Shi contributed equally to this work.

Authors and Affiliations

Department of Otolaryngology and Head and Neck Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China

Yiqi Pan, Zhihong Shi, Bin Ye, Yilin Shen & Mingliang Xiang

Department of Pathology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China

Qian Da & Chaofu Wang

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Contributions

Mingliang Xiang performed the whole operation and checked the final review. Yilin Shen revised and reviewed the original manuscript. Yiqi Pan wrote the whole manuscript. Zhihong Shi took part in the whole operation and carried out the literature review. Bin Ye reviewed the manuscript. Chaofu Wang and Qian Da provided the pathological images. All authors read and approved the final manuscript.

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Correspondence to Yilin Shen or Mingliang Xiang .

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The studies involving human participants were reviewed and approved by Human Ethics Committee, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine. The patient provided his written informed consent for the use of his images and other clinical information in this study. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

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Pan, Y., Shi, Z., Ye, B. et al. Surgical intervention of Lemierre’s syndrome: a case report and review of the literature. J Med Case Reports 18 , 265 (2024). https://doi.org/10.1186/s13256-024-04584-2

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SYSTEMATIC REVIEW article

Pd-l1 expression as a potential predictor of immune checkpoint inhibitor efficacy and survival in patients with recurrent or metastatic nasopharyngeal cancer: a systematic review and meta-analysis of prospective trials.

• 1 Department of Clinical Oncology, Li Ka Shing (LKS) Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong, Hong Kong SAR, China
• 2 School of Nursing, Li Ka Shing (LKS) Faculty of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong, Hong Kong SAR, China

Background: The predictive value of programmed death-ligand 1 (PD-L1) expression in nasopharyngeal cancer (NPC) patients receiving immune checkpoint inhibitors (ICIs) remains controversial. This study aimed to evaluate the optimal threshold of PD-L1 expression in predicting the efficacy of ICIs in patients with recurrent or metastatic (R/M) NPC.

Methods: A meta-analysis was performed by retrieving relevant literature from PubMed, EMBASE, and Cochrane Library databases. Data on the pooled risk ratio (RR), mean overall survival (OS), progression-free survival (PFS), overall response rate (ORR) with 95% confidence interval, and 1%, 10%, and 25% PD-L1 expression cutoff points were obtained to examine the role of PD-L1 as a biomarker in R/M NPC patients receiving immunotherapy.

Results: In total, 1,312 patients from 14 studies were included. An improvement in PFS was observed in both patients with PD-L1 ≥ 1% (RR = 0.76, 95% CI 0.62–0.92, P = 0.005) and those with PD-L1 < 1% (RR = 0.68, 95% CI: 0.35–1.32, P = 0.26) who received first-line treatment with immunotherapy, with no significant difference between these subgroups. The pooled ORR was significantly higher in patients with PD-L1 ≥ 1% (ORR = 0.37) than in those with PD-L1 < 1% (ORR = 0.22) (P < 0.01) undergoing subsequent-line treatment. However, when we used the PD-L1 cutoff values of 10% and 25%, there was no significant difference between the positive (PD-L1 expression ≥ the cutoff value) and negative (PD-L1 expression < the cutoff value) subgroups. PD-L1 ≥ 1% also tended to be associated with better PFS and OS.

Conclusions: Our meta-analysis suggested that first-line immunotherapy could significantly improve PFS in R/M NPC patients, regardless of the PD-L1 expression levels. Positive PD-L1 expression (≥ 1%) might be a potential predictive biomarker for a better overall response to immunotherapy in R/M NPC patients in subsequent-line setting.

Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024495841 PROSPERO, identifier CRD42024495841.

1 Introduction

Nasopharyngeal carcinoma (NPC) is a common type of head and neck cancer with a skewed geographical, ethnic, and sex distribution. It is particularly prevalent in east and southeast Asia, where the highest age-standardized rates occur ( 1 ). According to GLOBOCAN 2020 data, approximately 133,354 new cases and 80,008 deaths from NPC were reported worldwide, of which 62,444 cases (46.8%) and 34,810 deaths (43.5%) were registered in China ( 2 ).

In the past decade, the global incidence and mortality rates of NPC have gradually declined ( 3 ), which could be attributable to lifestyle and environmental changes, the use of intensity-modulated radiation therapy, and the increasing application of adjuvant chemotherapy ( 4 , 5 ). However, approximately 15%–30% of patients who develop recurrent or metastatic (R/M) NPC have a median overall survival (OS) of less than 2 years ( 6 ). The main challenges in treating these patients are overcoming chemo-resistance and reducing the risk of adverse events ( 7 ). Currently, immunotherapies, especially immune checkpoint inhibitors (ICIs), represent a promising strategy to resolve these problems and effectively treat R/M NPC patients.

ICIs, particularly anti-programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) and anti-cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) antibodies, which activate CD8-positive T cells and induce cancer cell mortality, have revolutionized the treatment of advanced cancers. The tumor microenvironment of NPCs, characterized by massive inflammatory and immune cell infiltration, allows NPC patients to fully benefit from ICI therapy. ICIs have emerged as effective treatment options for patients with refractory R/M NPC. More recently, the Food and Drug Administration (FDA) approved toripalimab as a treatment for R/M NPC to be used in combination with first-line chemotherapies or subsequent-line monotherapies ( 8 ). The National Comprehensive Cancer Network (NCCN) Guidelines version 2.2024 refer to cisplatin/gemcitabine combined with ICIs as the first-line treatment in the management of R/M NPC ( 9 ). However, only about 50% of patients respond to treatment, indicating the major challenge of identifying patients who are suitable for immunotherapy ( 6 ).

The level of PD-L1 expression is one of the most commonly explored predictive biomarkers for the success of ICIs. Previous studies have shown that higher PD-L1 expression levels are associated with a higher response rate and better survival in patients with advanced stage melanoma treated with ICIs ( 10 – 13 ). However, the predictive value of PD-L1 expression in NPC patients receiving ICIs remains controversial ( 14 – 16 ). Currently, there is no report of studies exploring the optimal cutoff value of PD-L1 expression to guide the clinical use of ICIs.

In this systematic review (SR), we comprehensively evaluated whether the expression level of PD-L1 influences the efficacy of anti-PD-1/PD-L1 monotherapy or combined therapy in NPC patients. Furthermore, subgroup analyzes were performed to assess and quantify the best cutoff value for PD-L1-positive tumors to guide future clinical practice.

2 Materials and methods

The study was reported in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyzes (PRISMA) ( 17 ). The protocol for this SR and meta-analysis was registered in PROSPERO (no.: 495841).

2.1 Eligibility criteria

To be eligible for this SR, studies were required to satisfy the following Population, Intervention, Comparison, Outcomes, and Study design (PICOS) criteria. Patients with a pathological diagnosis of R/M NPC who received immunotherapy with/without other systematic treatments were included. The included studies were required to report at least one clinical outcome, namely OS, progression-free survival (PFS), or overall response rate (ORR), based on the PD-L1 expression levels of patients. Randomized control trials (RCTs) and non-RCTs were considered eligible. There was no restriction on the language or publication status of studies. Patients receiving radiotherapy were not eligible for this SR. Review articles, case reports, conference abstracts, protocols, editorials, and commentaries were also excluded.

2.2 Literature search

A comprehensive literature search was performed on PubMed, Embase, and the Cochrane Library to identify potential eligible studies published from January 2013 to December 6, 2023. We also manually searched for eligible studies by checking the reference lists of retrieved studies to minimize the risk of missing relevant information. The detailed search strategy is described in Supplementary File 1 .

2.3 Literature selection

The titles and abstracts of potential studies were screened independently by two authors (C.H.L.W. and S.K.CH.), and then their full texts were assessed for eligibility. If there was any dispute, it was resolved through discussion between the two authors. A third author (C.L.C.) was consulted to settle unresolved disagreements.

A list of studies for inclusion was generated. For duplicate studies, the most recent and comprehensive version of each was selected for inclusion. SRs identified during the search were examined to ensure that no eligible studies were omitted.

2.4 Data extraction

Data were extracted by one author (R.Y.X.) and cross-reviewed by the other two authors (C.H.L.W. and S.K.CH.). Key information, including authors’ details, year of publication, study population, sample size, patient characteristics, follow-up time, intervention, and results of all prespecified outcomes, were extracted from each eligible study using a pre-designed data-extraction table.

2.5 Methodological quality assessment

The methodological quality of all included studies was evaluated by two reviewers (C.H.L.W. and R.Y.X.) independently using the Cochrane’s Risk of Bias in Randomized Trials (RoB 2) tool for RCTs ( 18 ) and the Cochrane’s Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) tool for non-randomized studies ( 19 ). For the included single-arm non-randomized studies, risk of bias was assessed using a modified ROBINS-I approach ( 20 ). The risk of bias was categorized as low, moderate, serious, or critical. Publication bias was assessed using Egger’s regression test and through a visual inspection of funnel plot asymmetry if there were more than 10 studies ( 21 ).

2.6 Data analysis

To examine the role of PD-L1 among R/M NPC patients receiving immunotherapy with/without other systematic treatment, we conducted a pairwise random-effects meta-analysis comparing immunotherapy plus chemotherapy patients with controls in the first-line therapy setting using RevMan version 5.4. We used pooled risk ratios (RRs) with 95% confidence intervals (CIs) to present PFS data.

Single-arm random-effects meta-analyzes were performed to synthesize the effects of immunotherapy with/without other systematic treatments on the clinical outcomes (i.e. OS, PFS, and ORR) in both first-line and subsequent-line settings using R version 4.2.3. The pooled estimated mean OS and PFS, as well as the pooled ORR with 95% CI, are presented.

For both pairwise and single-arm meta-analyzes, subgroup analysis was performed on each clinical outcome by stratifying patients into two groups (1): PD-L1 positive and (2) PD-L1 negative. Three cutoff points for PD-L1 expression level were used: 1%, 10%, and 25%. We also conducted a sensitivity analysis of the impact of treatments on the clinical outcomes by excluding patients who received combined immunotherapies and targeted therapies. We used I 2 values to quantify the level of heterogeneity, with I 2 < 25% indicating a low level of heterogeneity, 25%–50% indicating a moderate level of heterogeneity, and >50% indicating a high level of heterogeneity ( 22 ).

3.1 Literature search and selection

The literature search yielded 488 citations, among which 99 duplicate studies were removed. After screening the titles and abstracts, 116 eligible articles remained. As the full texts of 15 articles were not available, only 101 remaining papers proceeded to full-text assessment. Eighty-nine of these were excluded because (i) no recurrent or metastatic NPC adult patients were included (n = 22); (ii) treatment included radiotherapy or other therapies (n = 38); (iii) PD-L1 outcomes were not reported (n = 22); or (iv) they were retrospective studies (n = 7). With the identification of one additional reference through manual searches of the reference lists of included studies, a total of 14 studies in 13 articles were included in this systematic review. Details of the literature search and study selection are shown in the PRISMA flow diagram ( Figure 1 ) ( 23 ).

Figure 1 Flow diagram of meta-analysis for inclusion/exclusion of studies.

3.2 Characteristics of the included studies

Basic information on the qualified studies analyzed in this meta-analysis is available in Table 1 . One study was an RCT ( 24 ), two were non-randomized studies ( 25 , 29 ), and 11 were single-arm studies reported in 10 articles ( 26 – 28 , 30 – 36 ). All of the included studies were published between 2017 and 2023, with a majority of them conducted on Asian patients ( 24 – 28 , 30 – 36 ). The total sample size of the included studies was 1,434 patients, with six studies having a sample size of more than 100 ( 24 , 25 , 28 , 29 , 31 , 32 ). The follow-up period ranged from 1.0 to 2.5 years. Five studies used combined therapy as the intervention ( 24 , 25 , 33 , 34 , 36 ), while eight studies treated patients with mono-immunotherapy ( 26 – 32 , 35 ). These studies used different PD-L1 measurements, with four of them using 22C3 ( 26 , 29 , 30 , 36 ) (full details are provided in Table 2 ). Among all of these studies, 11 reported ORR ( 26 – 36 ), while 10 reported PFS ( 24 , 25 , 27 , 29 – 34 , 36 ) and five reported OS ( 27 , 29 – 32 ) based on PD-L1 expression. The overall risk of bias of eight studies (61.5%) ( 24 – 27 , 30 , 32 , 35 , 36 ) was considered low, but that of five studies (38.5%) was moderate ( 28 , 29 , 31 , 33 , 34 ), four of which were due to missing data ( Supplementary Table 1 ).

Table 1 Characteristics of the studies included in the meta-analysis.

Table 2 Technical information of PD-L1 measurement in the included studies.

3.3 Results of first-line treatment

Two studies of first-line therapy that included 505 patients reported PD-L1 levels and related PFS outcomes. As depicted in Figure 2A , the pooled results showed that ICIs significantly prolonged PFS (RR = 0.74, 95% CI: 0.60–0.90, P = 0.003). An improvement in PFS was observed in both patients with PD-L1 ≥ 1% (RR = 0.76, 95% CI 0.62–0.92, P = 0.005) and those with PD-L1 < 1% (RR = 0.68, 95% CI: 0.35–1.32, P = 0.26), with no significant difference between these subgroups. When using the PD-L1 cutoff of 10%, which was only used in the “RATIONAL 309” study, there was a tendency toward better PFS in PD-L1-positive patients, with RRs of 0.78 (95% CI: 0.64–0.95, P = 0.01) and 0.87 (95% CI: 0.63–1.19, P = 0.38) for PD-L1 ≥ 10% and PD-L1 < 10%, respectively ( Figure 2B ).

Figure 2 Forest plot of RR of PFS after first-line treatment. (A) 1% cut off; (B) 10% cutoff. PDL1, programmed cell death ligand-1; RR, risk ratio; PFS, progression-free survival.

3.4 Results of subsequent-line treatments

Twelve studies with 929 patients were included in this meta-analysis of first- or subsequent-line treatment. The PD-L1 levels reported in these studies were graded using different standards (PD-L1-positive at > 1% TC/IC (n = 10) ( 26 – 28 , 30 – 36 ), PD-L1-positive at > 10% TC/IC (n = 4) ( 29 , 32 , 34 , 35 ), and PD-L1 positive at > 25% TC/IC (n = 3) ( 28 , 30 , 34 ).

3.4.1 ORR of PD-L1 status after subsequent-line treatment

The forest plots show that the pooled ORR was significantly higher for NPC patients with PD-L1 ≥ 1% (ORR = 0.37, 95% CI: 0.29–0.46) than for those with PD-L1 < 1% (ORR = 0.22, 95% CI: 0.17–0.28) (subgroup difference, P < 0.01) ( Figure 3A ).

Figure 3 Forest plot of pooled results of ORR following subsequent-line treatment. (A) 1% cutoff; (B) 10% cutoff; (C) 25% cutoff.

Using a PD-L1 cutoff value of 10% resulted in a similar pattern ( Figure 3B ) (ORR = 0.43, 95% CI: 0.26–0.61 vs ORR = 0.36, 95% CI: 0.13–0.68). Using the 25% threshold for PD-L1 also revealed similar findings, with an ORR of 0.46 (95% CI: 0.24–0.69) in the PD-L1 ≥ 25% subgroup vs an ORR of 0.34 (95% CI: 0.13–0.64) in the PD-L1 < 25% subgroup ( Figure 3C ). However, as a result of the limited sample sizes and significant heterogeneity, differences between the subgroups were not statistically significant. We also noticed that the ORR appeared to rise with increasing PD-L1 expression level, suggesting that the efficacy of ICIs in NPC patients was correlated with PD-L1 expression levels.

To further elucidate the heterogeneity among these studies, sensitivity analysis was performed by excluding patients who received combined immunotherapy and targeted therapy. The results still showed a better ORR (0.29 vs 0.20) for PD-L1-positive patients who received ICI monotherapy, with significantly reduced heterogeneity (I 2  = 0% in both the groups, subgroup difference P = 0.03) ( Figure 4A ). Additionally, ORR improvement was more pronounced in the PD-L1-positive group vs the PD-L1-negative group for subsequent-line ORR with PD-L1 status of 10% (ORR = 0.34, 95% CI: 0.23–0.47 vs ORR = 0.20, 95% CI: 0.12–0.31, P = 0.07) ( Figure 4B ) and for subsequent-line ORR with PD-L1 status of 25% (ORR = 0.35, 95% CI: 0.20–0.52 vs ORR = 0.20, 95% CI: 0.15–0.26, P = 0.07) ( Figure 4C ).

Figure 4 Forest plot of ORR in sensitivity analysis excluding patients who received combined immunotherapy and targeted therapy as subsequent-line treatments. (A) 1% cutoff; (B) 10% cutoff; (C) 25% cutoff.

3.4.2 PFS and OS association with PD-L1 status after subsequent-line treatment

Eight studies reported the PFS and four reported the OS related to a PD-L1 cutoff of 1%. The PFS and OS results showed similar findings that both mean PFS (4.61 months, 95% CI: 2.60–6.62) and OS (17.56 months, 95% CI: 15.09–20.02) for NPC patients with PD-L1 ≥ 1% were longer than those for patients with PD-L1 < 1% (PFS: 3.39 months, 95%CI: 2.36–4.42; OS: 13.5 months, 95% CI: 6.65–20.35), but there was no significant subgroup difference ( Figures 5 , 6 ).

Figure 5 Forest plot showing pooled results of PFS after subsequent-line treatment (1% cutoff).

Figure 6 Forest plot of pooled results of OS after subsequent-line treatment (1% cutoff).

3.5 Publication bias

Publication bias was assessed with an Egger’s regression plot for 12 articles focusing on subsequent-line therapy. The plot revealed no presence of publication bias (P = 0.13), and no asymmetry was found in the funnel plot ( Figure 7 ).

Figure 7 Funnel plot of publication bias.

4 Discussion

To the best of our understanding, this is the first in-depth analysis of the predictive value of PD-1/PD-L1 status in clinical trials of immunotherapy and combined therapy for patients with advanced metastatic NPC. We comprehensively evaluated the correlation between different expression levels of PD-L1 and the ORR, PFS, and OS of R/M NPC patients, with data retrieved from 14 studies that included 1,434 patients in total. We aimed to determine the predictive value of PD-L1 and to identify an optimal PD-L1 cutoff value for the selection of patients likely to respond effectively to anti-PD-1/PD-L1 treatment.

The NCCN guidelines only recommend to use i) cisplatin/gemcitabine alone, or ii) cisplatin/gemcitabine plus toripalimab, or iii) cisplatin/gemcitabine plus the other PD-1 inhibitors (pembrolizumab or nivolumab) as first-line therapies for R/M NPC ( 9 ). In our analysis of the two included studies in the first-line setting, the use of ICIs could significantly improve PFS, regardless of the PD-L1 expression levels. Various ICI monotherapies (toripalimab, pembrolizumab or nivolumab) are recommended as subsequent-line therapy based on the PD-L1 expression levels in NCCN guidelines ( 9 ). The availability of ample subsequent-line treatment data gave us the opportunity to draw more precise and accurate conclusions. The most compelling finding in our study was that patients with PD‐L1 ≥ 1% who received ICI in the subsequent-line setting had significantly higher ORR than in those with PD-L1 < 1%. Our pooled results showed no significant difference between subgroups in analysis of PFS and ORR for PD-L1 cutoff value of ≥ 10%, and ≥ 25%. However, higher the PD-L1 expression, the higher the probability that the patient was able to achieve clinical benefit from ICIs in the subsequent-line setting.

ICIs, which reactivate immune response in the tumor by preventing immunosuppressive factors from binding to their ligands, have fewer side effects compared to chemotherapy ( 37 ). Side effects of ICIs are usually mild. The most common side effects include fatigue, itchy rash, and diarrhea ( 38 ). In addition, as ICIs may also activate autoreactive T cells, they increase the risk of immune-related adverse events (irAEs). In our included studies, irAEs such as hypothyroidism, aspartate aminotransferase(AST) level increased, and rash, were also frequently reported. The detail information is shown in Table 1 .

PD-L1, the most common immunosuppressive ligand, expressed on the tumor cell membrane combines with the PD-1 of tumor-infiltrating lymphocytes (TIL), contributing to tumor cell evasion from host immune system surveillance ( 39 ). In previous studies, high expression of PD-L1 appeared to adversely affect the survival outcomes of NPC patients. A meta-analysis involving 13 studies showed that PD-L1 over-expression in NPC was associated with a poor OS (hazard ratio = 1.48, 95% CI: 1.00–2.18, P = 0.049) ( 40 ). Another study discovered a significant correlation between high PD-L1 expression and a short PFS/OS ( 41 ). In contrast to previous studies that examined the prognostic value of PD-L1 in patients with NPC, our study evaluated the predictive value of PD-L1 expression for ICI therapy. The results provide evidence that PD-L1-positive patients received more benefit than PD-L1-negative patients at a PD-L1 cutoff value of 1%, which sets a preliminary framework for the R/M NPC patient population suitable for ICI treatment. However, as the cutoff values varied across articles, coupled with the fact that 1% was the most widely used expression-level cutoff for PD-L1 detection, more comprehensive studies on PD-L1 expression levels and ICI treatment efficacy are warranted to accurately validate these results.

Moreover, the PD-L1 expression on ICIs effect shows differences between first-line treatment and subsequent-line treatment, which may be caused by many factors. First, it is known that tumor progression is influenced by the tumor immune microenvironment, one of the important mechanisms is escape from immune surveillance with the selection of poorly immunogenic cells ( 42 , 43 ). When the disease becomes refractory, the tumor microenvironment (TME) becomes more immune-suppressive. As a result, in the first-line setting when TME is still favorable, the immunotherapy-chemotherapy combination would improve survival regardless of PD-L1 expression. However, in subsequent line settings when TME becomes more immunosuppressive, only those with higher PD-L1 expression derived benefit from checkpoint inhibitors.

Second, all first-line trials evaluate the immunotherapy-chemotherapy combination while most later-line studies are using immunotherapy-alone ( 44 ). Chemotherapy could activate the T-cell priming and recruitment and works synergistically with immunotherapy, therefore patients who accept first-line treatment of immunotherapy-chemotherapy combination would respond to the treatment regardless of PD-L1 expression.

Though PD-L1 is the most widely studied biomarker for immunotherapy, additional biomarkers have been evaluated in several studies. For instance, a meta-analysis showed that patients with lower baseline plasma Epstein-Barr virus (EBV) DNA levels had a higher ORR and longer median PFS than those with higher EBV DNA levels, but tumor mutational burden (TMB) was not significantly correlated with clinical prognosis in NPC patients treated with ICIs ( 16 ). Furthermore, a statistical difference in PFS was observed between patients with tumors showing loss of HLA-A and/or HLA-B expression, and patients with tumors expressing both HLA-A and HLA-B in trial NCI-9742 ( 26 ). A single-arm phase II clinical trial indicated that, in R/M NPC patients, a strong suppression of TGFβ1 levels was associated with worse ORR and PFS ( 30 ).

With the development of bioinformatics and biotechnologies, novel forms of biomarkers, such as mutations/chromosomal abnormalities, have been made available that provide new perspectives on precision medicine. A recent clinical trial revealed that 11q13.3 focal amplification and high MRGPRF expression are predictive of poor outcomes following gemcitabine plus apatinib and toripalimab therapy, but in another study (POLARIS-02), the genomic alternations had no statistically significant associations with clinical efficacy ( 28 , 33 ). However, our study of the PD-L1 biomarker has particular clinical relevance. PD-L1 status is readily used in clinical settings, as the technology is well established and inexpensive.

Our meta-analysis has several limitations. First, there was significant variability in the literature with regards to the prevalence and prognostic significance of PD-L1 expression in NPC patients, probably because of differences in the assays and scoring methods used across studies. However, in a cross-correlation study performed using different PD-L1 immunohistochemical assays, the JS311 antibody had similar PD-L1 staining patterns and scores to the antibodies 22C3, 28–8, and SP263 ( 45 ). The predictive utility of PD-L1 expression may also depend on its differential expression in immune cells versus tumor cells. Second, there was a lack of sufficient clinical trials of first-line treatments reporting OS and ORR in patients with different PD-L1 expression levels that could be included in our analysis. Despite the encouraging outcomes, the limited number of articles means we are skeptical of the conclusions, and more clinical trials focusing on ICI treatments are needed for further validation. Third, only three and two studies were included in the analysis of the PFS and OS, respectively, for the PD-L1 10% level. More clinical trials are needed to further enrich and validate our conclusions and better guide the use of clinical PD-L1 levels to maximize the benefits and reduce the side effects of ICIs. Lastly, most of the studies included were conducted in Asian populations, and the regional characteristics of NPC may limit the generalizability of our findings.

5 Conclusions

Our meta-analysis suggested that first-line immunotherapy could significantly improve PFS in R/M NPC patients, regardless of the PD-L1 expression levels. Nonetheless, positive PD-L1 expression (≥ 1%) might be a potential predictive biomarker for a better response to immunotherapy in R/M NPC patients in subsequent-line setting. The higher the PD-L1 expression, the higher the probability that the patient was able to achieve clinical benefit from subsequent-line treatment.

Data availability statement

The original contributions presented in the study are included in the article/ Supplementary Material . Further inquiries can be directed to the corresponding author.

Author contributions

RX: Data curation, Investigation, Methodology, Visualization, Writing – original draft, Writing – review & editing. CW: Data curation, Formal analysis, Investigation, Methodology, Software, Validation, Writing – review & editing. KC: Investigation, Methodology, Validation, Writing – review & editing. CC: Conceptualization, Funding acquisition, Project administration, Supervision, Writing – review & editing.

The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.

Acknowledgments

We sincerely thank all authors and study participants for their support in the study. Professional English language editing support provided by AsiaEdit (asiaedit.com).

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Supplementary material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fonc.2024.1386381/full#supplementary-material

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Keywords: nasopharyngeal carcinoma, recurrence or metastasis, PD-L1, immune checkpoint inhibitors, meta-analysis

Citation: Xu R, Wong CHL, Chan KSK and Chiang CL (2024) PD-L1 expression as a potential predictor of immune checkpoint inhibitor efficacy and survival in patients with recurrent or metastatic nasopharyngeal cancer: a systematic review and meta-analysis of prospective trials. Front. Oncol. 14:1386381. doi: 10.3389/fonc.2024.1386381

Received: 15 February 2024; Accepted: 20 May 2024; Published: 03 June 2024.

Reviewed by:

Copyright © 2024 Xu, Wong, Chan and Chiang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Chi Leung Chiang, [email protected]

† These authors have contributed equally to this work and share first authorship

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

International Prehospital Medicine Institute Literature Review, June 2024

This literature review keeps you up to date with current EMS publications and studies.

1. Accuracy of Prehospital Services’ Estimated Time to Arrival for Ground Transport to the Emergency Department . Fozard J, Becker B, Lurie T, Dasti A.    J Emerg Med 2024;66: e581–e588

2. Prehospital Administration of Norepinephrine and Epinephrine for Shock after Resuscitation from Cardiac Arrest. Wender ER, Counts CR, Van Dyke M, Sayre MR, Maynard C, Johnson NJ.  Prehosp Emerg Care 2024;28:3, 453-458.

3. Tranexamic Acid for Traumatic Injury in the Emergency Setting: A Systematic Review and Bias-Adjusted Meta-Analysis of Randomized Controlled Trials .  Jarvis JL, Panchal AR, Lyng JW, et al. Ann Emerg Med 2024;83:435-445.

4. Evidence-Based Guideline for Prehospital Airway Management.  Reiter A, Strahl A, Kothe S, et al. Prehosp Emerg Car, 2024;28:4, 545-557.

International Prehospital Medicine Institute Literature Review, May 2024

The efficient functioning of every Emergency Department (ED) depends on several factors, including anticipation of patient in-flow that allows for accurate allocation of resources. The accuracy of the estimated time of arrival (ETA) given by EMS while en route to the ED is important to ensure that personnel aren’t diverting time and attention from other patients while waiting for EMS to arrive. An overestimated ETA results in the patient arriving earlier than expected by the ED, potentially leaving the staff unprepared to render care in a timely manner. An underestimated ETA may redirect personnel from other patients while waiting for EMS arrival.

This study is a single-center, prospective, observational study examining the accuracy of ETA reported by EMS ground ambulances transporting patients to the ED. The study ED is large, Level 1 trauma center, regional chest pain center, and certified stroke center in a medium-sized community in Pennsylvania. The catchment area is a mix of urban, suburban, and rural areas with transport times ranging from less than 5 minutes to greater than 45 minutes. The authors excluded helicopter transports and any alert with missing data. The ETA was recorded by an ED nurse or clerk, as were patient demographics. The actual time of arrival (ATA) was defined as the time the patient arrived and a time-stamp was generated by the ED. The primary study outcome measure was the median difference between the ETA and the ATA. Secondary outcome measured were the differences between ETA and ATA among select subgroups, including medical vs trauma patients, suspected acute coronary syndromes (ACS), suspected strokes, and cardiac arrests. The study occurred over four months: August and December 2018, and January and February 2019.

A total of 1176 transports were included for analysis. Medical transports comprised 86% of patients, while trauma accounted for 14%. Subgroups included trauma activations (1.7%), ACS (9.4%), stroke (2.4%), and cardiac arrest (0.6%). Statistically significant differences between ETA and ATA were noted for all groups.  The overall median difference between ETA and ATA was 3 minutes. EMS underestimated the ETA in 81.7% of cases and overestimated the ETA in 10.3% of cases. EMS was correct within 1 minute in 8% of cases. Based on time of day, the largest median difference was from 16:00-16:59 (5 minutes) and 07:00-07:59 (4.75 minutes). The smallest differences occurred between 06:00-06:59 and 09:00-09:59 (2 minutes).

This study has several weaknesses. It is a single center study, and its results may not translate to hospitals in different geographic areas, such as purely urban or rural. It only occurred over a 4-month period, so discrepancies could occur during other months. Approximately 25% of calls were missing data and not included in the study. Multiple staff collected the data so methods may not have been consistent. Computerized Global Positioning System (GPS)-based navigation technology is widely available, but the extent of its use in this study is unclear.

This study demonstrates that EMS personnel are relatively accurate in predicting their time of arrival. It is a good example of a study in which the results may be statistically significant, but that doesn’t mean they are clinically significant. The median difference between ETA and ATA was only 3 minutes and is unlikely to disrupt the workflow of ED personnel. It is a good study to help dispel the myth that EMS personnel are unable to accurately estimate their ETA to the hospital.

The goal of management of every out of hospital cardiac arrest (OHCA) is to obtain the return of spontaneous circulation (ROSC).  Ideally ROSC should be sustainable and result in the patient’s eventual discharge from the hospital neurologically intact.  It is not uncommon for a period of shock state immediately following ROSC.  Similarly, OHCA patients may rearrest prior to arrival at a hospital. 

This was an institutional review board approved retrospective study of one EMS agency’s OHCA data for the eight year period ending December 2021.  The authors of this study compared rearrest rates between patients that were given epinephrine and norepinephrine to treat immediate post arrest shock.  Both medications are vasopressors that target beta-1 adrenergic and alpha-1 adrenergic receptors.  The difference between the two is epinephrine’s greater affinity for beta-1 adrenergic receptors and norepinephrine’s primary alpha-1 effects.  The choice of vasopressor was left to the field provider in collaboration with an on-line medical control physician.  Both epinephrine (2mg / 250 ml D5W) and norepinephrine (8 mg / 250 ml D5W) were infused via micro drip tubing and titrated by hand to maintain a systolic blood pressure of 90 mmHg.  Infusion pumps were not used to control either vasopressor. Hospital data were available to the researchers via a robust system wide cardiac arrest registry.

In total 3,679 OHCA patients were treated. Of these, 3,288 were excluded.  Exclusion criteria included pediatric patients, patients without ROSC, basic life support care only, patients with do not resuscitate orders, patients who did not receive epinephrine or norepinephrine infusions, patients who received both vasopressors and patients dead on scene or whom resuscitation was terminated in the field. This resulted in 451 patients included in the study, 253 (56%) received norepinephrine and 198 (44%) received epinephrine infusions. 

Patient demographics were similar between both vasopressor groups.  It was noted that the norepinephrine group were slightly younger, median age of 63 versus 67.  Almost all patients were treated with an advanced airway (99%).  The most common advanced airway was an endotracheal tube (94%).  Most (82%) received their advanced airway prior to the administration of a vasopressor.

Patients in the epinephrine group were more likely to rearrest by a substantial margin (55% vs 25%).  Subsequently, incidence of pulses upon arrival at the hospital were lower in the epinephrine group.  For patients that did arrive at the hospital with sustained ROSC, there was no difference in survival to discharge (14%) or favorable neurological status (10%) at discharge (Cerebral Performance Category score of 1 or 2).

The authors acknowledge several limitations of their work.  The first being the retrospective design of their study. The choice of vasopressor was at the paramedic discretion and not randomized. The largest limitation is the system’s lack of infusion pumps during the study period.  Due to this limitation no exact doses of epinephrine or norepinephrine were documented.  Timing of the vasopressor infusion was not recorded. Patients may have received the vasopressor infusion after they had experienced a rearrest.

The authors found that epinephrine given as a post arrest vasopressor infusion resulted in a higher rearrest state for OHCA patients after ROSC was obtained.  They advocate for future randomized control studies comparing these commonly used vasopressors.  Field providers and medical directors should consider the options for vasopressors within their EMS system, and which works best for unique patient groups.  Ideally, all prehospital medication infusion should be administered via an IV pump or controller to ensure accurate dosing of the medication.

Tranexamic acid (TXA) is an antifibrinolytic medication which prevents the breakdown of clot and reduces bleeding.  It has been advocated for use in most, if not all, trauma victims. 

The authors of this paper sought to compare TXA to placebo by performing a systematic review and meta-analysis combining updated data on the benefits of TXA?”  Two researchers working independently performed comprehensive reviews of Medline, EMBASE and the Cochrane Central Register of Controlled Trials from their inception up to May 1, 2023.  Studies included for analysis were randomized controlled trials.  The primary outcome measure was 1-month mortality and secondary outcomes included 24-hour mortality and vascular occlusive events at 1-month including myocardial infarction, stroke, deep venous thrombosis and pulmonary embolism.

The search identified 363 articles and after abstract screening and removing duplicates, 7 trials were included in their review and analysis. All seven of these were randomized double blinded studies. Three of the studies were conducted in prehospital settings and none included pediatric patients. Three were on general trauma and the other four focused on brain injuries.

Regarding the primary outcome of one-month and 24-hour mortality, the analysis suggested a moderate benefit for TXA (OR .89). This would amount to preventing one additional death per month per 61 patients treated with TXA. In looking at the four trials that reported 24-hour mortality, a similar moderate benefit was found for TXA. They did not demonstrate evidence of an increase in vascular occlusive events.

In looking at the timing of TXA administration, there were insufficient studies reporting on the administration of TXA more than 3-hours post injury to allow meta- analysis. They did point out that the CRASH-2 trial reported an 11% reduced risk of death when TXA is administered less than 3 hours post trauma compared to those that received it after 3 hours. The CRASH-3 trial looking at TBI patients described a benefit for mild and moderate head injury patients who received TXA early.

In comparing in-hospital versus prehospital data, the odds of death for the prehospital patients were 22% less with TXA versus placebo while for in-hospital patients TXA patients had a 9% less chance of death over those receiving a placebo.

The limitation of this study was the inability to pool patient-centered outcomes such as neurologic status as the trials did not include this in their reporting.  In addition, no information was provided about the fibrinolytic status of the patients which could introduce significant heterogeneity to the study groups and affect the potential benefit of TXA.

This meta-analysis shows that patients receiving TXA had an 11% reduction in odds of death at 1-month over patients that received placebo, which when translated to the risk of death at one month comes to 1.7% fewer trauma deaths and which equates to 1 less death for every 61 trauma patients treated with TXA.  The results of this study are consistent with previous meta-analysis regarding TXA use in trauma patients. TXA appears to be more effective when used prehospital versus in-hospital.

Airway management of the critically ill or injured patient is one of the foundational aspects for successful patient outcomes.  However, in the last few years, the long-standing method of endotracheal intubation has come into question in the prehospital arena.  The goal of this paper was to review and grade the Agency for Healthcare Research and Quality (AHRQ) systematic review of currently available literature to develop a scientific basis for prehospital airway management protocols by a panel of experts in Emergency and EMS medicine, research and evidence evaluation. 

   For patients with out of hospital cardiac arrest (OHCA) both Bag-Valve-Mask (BVM) and Supraglottic Airway (SGA) devices are recommended options. Additionally, either BVM alone or Endotracheal Intubation (ETI) can be considered.  Both recommendations were considered conditional based on low to very low certainty of the evidence.  When ETI proficiency is lacking, SGA is preferred over ETI for adult OHCA cases, while in systems with high ETI proficiency, either SGA or ETI is suggested, with a conditional recommendation supported by low to moderate evidence.

For pediatric OHCA patients, both BVM and SGA are conditionally recommended, with very low evidence. BVM ventilation alone is favored over ETI, supported by low-level evidence, and SGA is preferred over ETI with a conditional recommendation and very low evidence.  

In adult trauma cases, either BVM or SGA devices are suggested for airway management, as a conditional recommendation with very low evidence. Ventilation with either BVM alone or Endotracheal Intubation (ETI) is also recommended, supported by low-level evidence. Additionally, either SGA or ETI can be considered for adult trauma cases, with a very low evidence base.

For pediatric trauma patients, there is insufficient evidence to recommend BVM alone over SGA. However, both BVM alone and ETI are suggested options for airway management, with a low-level evidence base. Favoring SGA over ETI is suggested, but with very low evidence.

Medical emergencies requiring airway management were also reviewed by the panel for both adult and pediatric groups.   This revealed that there was insufficient evidence in most categories to make recommendations regarding BVM alone.  They made conditional recommendations that either SGA or ETI could be performed for both adults and pediatrics with very low certainty of evidence. 

The authors note the major limitation of this paper is the lack of quality evidence for the scientific evaluation of prehospital airway management.  In all of the emergency situations presented, the airway management recommendations were conditional or no recommendation and the evidence certainty was low or very low.   This limitation, as with many other issues in prehospital care, points out the need for high quality, controlled studies to guide EMS Medical Directors and providers in the practice of prehospital medicine.

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