systematic literature review x narrative review

Turney, S. (2022, December 07). Systematic Review | Definition, Example & Guide. Scribbr. Retrieved February 27, 2023, from https://www.scribbr.com/methodology/systematic-review/

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Systematic Reviews

Breakdown of systematic reviews, other reviews, what review is right for you.

Timeline Table

Systematic Review Timeline Table PDF

What Is a Systematic Review?

A systematic review is a comprehensive literature review that seeks to answer a specific clinical question using existing research as evidence. According to Cook et. al (1997) , systematic reviews "can help practitioners keep abreast of the medical literature by summarizing large bodies of evidence and helping to explain differences among studies on the same question."

Systematic reviews are designed to:

For more information on systematic reviews and meta-analyses, visit Systematic reviews and meta-analyses: a step-by-step guide by Kate McAllister .

For reporting guidelines for systematic reviews and meta-analyses, visit PRISMA Transparent Reporting of Systematic Reviews and Meta-Analyses and the Equator Network .

How Long Do They Take to Complete?

Systematic reviews require a significant time commitment because of their standards and methodology requirements. Systematic reviews may take a review team an estimated 9-12 months to complete.

The average timeline for a systematic review is estimated below, as outlined in the Cochrane Handbook for Systematic Reviews of Interventions 2011:

Adapted from Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from handbook.cochrane.org.

Meta-Analysis

A meta-analysis is a type of systematic review that uses statistical methods to summarize the results of studies that meet the criteria for inclusion within the review.

For reporting guidelines for systematic reviews and meta-analyses, visit PRISMA Transparent Reporting of Systematic Reviews and Meta-Analyses .

For more information on analyzing data for systematic reviews, see Part 2 - Chapter 10 of the Cochrane Handbook for Systematic Reviews of Interventions .

Scoping Review

A scoping review provides an assessment of the potential size and scope of available research on a particular topic. Similar to a systematic review, a scoping review follows a predetermined search methodology and reporting process. Scoping reviews questions are often broader than systematic review questions, as they are designed to identify the "nature and extent of research evidence (usually including ongoing research)" (Grant and Booth, 2009). Scoping reviews can highlight areas where future systematic reviews can be conducted, or be used as standalone reviews when systematic reviews are not feasible to share findings, identify research gaps and make recommendations for future research (Peters et. al, 2015).

For more information on scoping reviews, please see the following articles:

Grant, M. J., & Booth, A. (2009). A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal , 26 (2), 91-108. DOI: 10.1111/j.1471-1842.2009.00848.x.

Peters, M. D., Godfrey, C. M., Khalil, H., McInerney, P., Parker, D., & Soares, C. B. (2015). Guidance for conducting systematic scoping reviews. JBI Evidence Implementation , 13 (3), 141-146. DOI: 10.1097/XEB.0000000000000050.

For reporting requirements for scoping reviews, please visit PRISMA for Scoping Reviews .

Rapid Review

A rapid review uses systematic review methods to provide quick yet thorough assessments of existing evidence surrounding a policy or practice issue. While a rapid review is designed to be conducted in less time than a systematic review, a rapid review incorporates systematic review methods to critically appraise research finding within included studies. A rapid review may use specified techniques to shorten the review timeframe, and the reviewer(s) must specifically report which stages to limit and the likely effects of those limitations (Grant and Booth, 2009).

For more information on rapid reviews, please see the following articles:

Garritty, C., Gartlehner, G., Nussbaumer-Streit, B., King, V. J., Hamel, C., Kamel, C., Affengruber, L., & Stevens, A. (2021). Cochrane Rapid Reviews Methods Group offers evidence-informed guidance to conduct rapid reviews. Journal of clinical epidemiology , 130 , 13–22. https://doi.org/10.1016/j.jclinepi.2020.10.007.

Grant, M. J., & Booth, A. (2009). A typology of reviews: an analysis of 14 review types and associated methodologies. Health information & libraries journal , 26 (2), 91-108. DOI: 10.1111/j.1471-1842.2009.00848.x.

Integrative Review

An integrative review summarizes both experimental, non-experimental, and theoretical literature to expand understanding surrounding a specific healthcare problem or phenomenon. According to Whittemore & Knafl (2005), integrative reviews have the potential to impact evidence-based practice for nursing because it is the only approach that allows for the combination of diverse methodologies.

For more information surrounding integrative reviews, please explore the following articles:

Toronto, C. E., & Remington, R. (Eds.). (2020). A step-by-step guide to conducting an integrative review . Cham, Swizterland: Springer International Publishing.

Whittemore, R., & Knafl, K. (2005). The integrative review: updated methodology. Journal of advanced nursing , 52 (5), 546–553. https://doi.org/10.1111/j.1365-2648.2005.03621.x

Narrative (Literature) Review

A narrative (literature) review is a form of knowledge synthesis surrounding a specific research question or issue. A narrative review does not require a systematic search of the literature and does not require included studies to be assessed for risk or bias. According to Ferrari (2015), narrative (literature) reviews are helpful for exploring general topics or debates, addressing more than one question, and identifying knowledge gaps and areas for future research.

For more information regarding narrative (literature) reviews, please see the following articles:

Ferrari, R. (2015). Writing narrative style literature reviews. Medical writing (Leeds), 24( 4), 230–235. https://doi.org/10.1179/2047480615Z.000000000329.

Which review is that? A guide to review types.

Narrative’ synthesis’ refers to an approach to the systematic review and synthesis of findings from multiple studies that relies primarily on the use of words and text to summarise and explain the findings of the synthesis. Whilst narrative synthesis can involve the manipulation of statistical data, the defining characteristic is that it adopts a textual approach to the process of synthesis to ‘tell the story’ of the findings from the included studies. As used here ‘narrative synthesis’ refers to a process of synthesis that can be used in systematic reviews focusing on a wide range of questions, not only those relating to the effectiveness of a particular intervention. (Popay et al. 2006)

Guidelines Campbell, M., McKenzie, J. E., Sowden, A., Katikireddi, S. V., Brennan, S. E., Ellis, S., ... & Thomson, H. (2020). Synthesis without meta-analysis (SWiM) in systematic reviews: reporting guideline. bmj , 368 . Full Text Other

Popay, J., Roberts, H., Sowden, A., Petticrew, M., Arai, L., Rodgers, M., ... & Duffy, S. (2006). Guidance on the conduct of narrative synthesis in systematic reviews. A product from the ESRC methods programme Version , 1 (1), b92. Full Text

Thomson H, Campbell M. “Narrative synthesis” of quantitative effect data in Cochrane reviews: Current issues and ways forward [Internet]. Cochrane Learning Live Webinar Series 2020 Feb. Full Text

Morley, G., Ives, J., Bradbury-Jones, C., & Irvine, F. (2019). What is 'moral distress'? A narrative synthesis of the literature. Nursing ethics , 26 (3), 646–662. https://doi.org/10.1177/0969733017724354 Full Text PDF

References Popay, J., Roberts, H., Sowden, A., Petticrew, M., Arai, L., Rodgers, M., ... & Duffy, S. (2006). Guidance on the conduct of narrative synthesis in systematic reviews. A product from the ESRC methods programme Version , 1 (1), b92. Full Text

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The difference between a systematic review and a literature review

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Home | Blog | Best Practice | The difference between a systematic review and a literature review

Covidence takes a look at the difference between the two

Most of us are familiar with the terms systematic review and literature review. Both review types synthesise evidence and provide summary information. So what are the differences? What does systematic mean? And which approach is best 🤔 ?

‘ Systematic ‘ describes the review’s methods. It means that they are transparent, reproducible and defined before the search gets underway. That’s important because it helps to minimise the bias that would result from cherry-picking studies in a non-systematic way.

This brings us to literature reviews. Literature reviews don’t usually apply the same rigour in their methods. That’s because, unlike systematic reviews, they don’t aim to produce an answer to a clinical question. Literature reviews can provide context or background information for a new piece of research. They can also stand alone as a general guide to what is already known about a particular topic.

Interest in systematic reviews has grown in recent years and the frequency of ‘systematic reviews’ in Google books has overtaken ‘literature reviews’ (with all the usual Ngram Viewer warnings – it searches around 6% of all books, no journals).

Let’s take a look at the two review types in more detail to highlight some key similarities and differences 👀.

🙋🏾‍♂️ What is a systematic review?

Systematic reviews ask a specific question about the effectiveness of a treatment and answer it by summarising evidence that meets a set of pre-specified criteria.

The process starts with a research question and a protocol or research plan. A review team searches for studies to answer the question using a highly sensitive search strategy. The retrieved studies are then screened for eligibility using the inclusion and exclusion criteria (this is done by at least two people working independently). Next, the reviewers extract the relevant data and assess the quality of the included studies. Finally, the review team synthesises the extracted study data and presents the results. The process is shown in figure 2 .

The results of a systematic review can be presented in many ways and the choice will depend on factors such as the type of data. Some reviews use meta-analysis to produce a statistical summary of effect estimates. Other reviews use narrative synthesis to present a textual summary.

Covidence accelerates the screening, data extraction, and quality assessment stages of your systematic review. It provides simple workflows and easy collaboration with colleagues around the world.

When is it appropriate to do a systematic review?

If you have a clinical question about the effectiveness of a particular treatment or treatments, you could answer it by conducting a systematic review. Systematic reviews in clinical medicine often follow the PICO framework, which stands for:

👦 Population (or patients)

💊 Intervention

💊 Comparison

Here’s a typical example of a systematic review title that uses the PICO framework: Alarms [intervention] versus drug treatments [comparison] for the prevention of nocturnal enuresis [outcome] in children [population]

Key attributes

🙋🏻‍♀️ What is a literature review?

Literature reviews provide an overview of what is known about a particular topic. They evaluate the material, rather than simply restating it, but the methods used to do this are not usually prespecified and they are not described in detail in the review. The search might be comprehensive but it does not aim to be exhaustive. Literature reviews are also referred to as narrative reviews.

Literature reviews use a topical approach and often take the form of a discussion. Precision and replicability are not the focus, rather the author seeks to demonstrate their understanding and perhaps also present their work in the context of what has come before. Often, this sort of synthesis does not attempt to control for the author’s own bias. The results or conclusion of a literature review is likely to be presented using words rather than statistical methods.

When is it appropriate to do a literature review?

We’ve all written some form of literature review: they are a central part of academic research ✍🏾. Literature reviews often form the introduction to a piece of writing, to provide the context. They can also be used to identify gaps in the literature and the need to fill them with new research 📚.

🙋🏽 Ok, but what is a systematic literature review?

A quick internet search retrieves a cool 200 million hits for ‘systematic literature review’. What strange hybrid is this 🤯🤯 ?

Systematic review methodology has its roots in evidence-based medicine but it quickly gained traction in other areas – the social sciences for example – where researchers recognise the value of being methodical and minimising bias. Systematic review methods are increasingly applied to the more traditional types of review, including literature reviews, hence the proliferation of terms like ‘systematic literature review’ and many more.

Beware of the labels 🚨. The terminology used to describe review types can vary by discipline and changes over time. To really understand how any review was done you will need to examine the methods critically and make your own assessment of the quality and reliability of each synthesis 🤓.

Review methods are evolving constantly as researchers find new ways to meet the challenge of synthesising the evidence. Systematic review methods have influenced many other review types, including the traditional literature review.

Covidence is a web-based tool that saves you time at the screening, selection, data extraction and quality assessment stages of your systematic review. It supports easy collaboration across teams and provides a clear overview of task status.

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Laura Mellor. Portsmouth, UK

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How to Conduct a Systematic Review: A Narrative Literature Review

Nusrat jahan.

1 Psychiatry, Mount Sinai Chicago

Sadiq Naveed

2 Psychiatry, KVC Prairie Ridge Hospital

Muhammad Zeshan

3 Department of Psychiatry, Bronx Lebanon Hospital Icahn School of Medicine at Mount Sinai, Bronx, NY

Muhammad A Tahir

4 Psychiatry, Suny Upstate Medical University, Syracuse, NY

Systematic reviews are ranked very high in research and are considered the most valid form of medical evidence. They provide a complete summary of the current literature relevant to a research question and can be of immense use to medical professionals. Our goal with this paper is to conduct a narrative review of the literature about systematic reviews and outline the essential elements of a systematic review along with the limitations of such a review.

Introduction and background

A literature review provides an important insight into a particular scholarly topic. It compiles published research on a topic, surveys different sources of research, and critically examines these sources [ 1 ]. A literature review may be argumentative, integrative, historical, methodological, systematic, or theoretical, and these approaches may be adopted depending upon the types of analysis in a particular study [ 2 ].

Our topic of interest in this article is to understand the different steps of conducting a systematic review. Systematic reviews, according to Wright, et al., are defined as a “review of the evidence on a clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant primary research, and to extract and analyze data from the studies that are included in the review” [ 3 ]. A systematic review provides an unbiased assessment of these studies [ 4 ]. Such reviews emerged in the 1970s in the field of social sciences. Systematic reviews, as well as the meta-analyses of the appropriate studies, can be the best form of evidence available to clinicians [ 3 ]. The unsystematic narrative review is more likely to include only research selected by the authors, which introduces bias and, therefore, frequently lags behind and contradicts the available evidence [ 5 ].

Epidemiologist Archie Cochrane played a vital role in formulating the methodology of the systematic review [ 6 ]. Dr. Cochrane loved to study patterns of disease and how these related to the environment. In the early 1970s, he found that many decisions in health care were made without reliable, up-to-date evidence about the treatments used [ 6 ].

A systematic review may or may not include meta-analysis, depending on whether results from different studies can be combined to provide a meaningful conclusion. David Sackett defined meta-analysis as a “specific statistical strategy for assembling the results of several studies into a single estimate” [ 7 - 8 ].

While the systematic review has several advantages, it has several limitations which can affect the conclusion. Inadequate literature searches and heterogeneous studies can lead to false conclusions. Similarly, the quality of assessment is an important step in systematic reviews, and it can lead to adverse consequences if not done properly.

The purpose of this article is to understand the important steps involved in conducting a systematic review of all kinds of clinical studies. We conducted a narrative review of the literature about systematic reviews with a special focus on articles that discuss conducting reviews of randomized controlled trials. We discuss key guidelines and important terminologies and present the advantages and limitations of systematic reviews.

Narrative reviews are a discussion of important topics on a theoretical point of view, and they are considered an important educational tool in continuing medical education [ 9 ]. Narrative reviews take a less formal approach than systematic reviews in that narrative reviews do not require the presentation of the more rigorous aspects characteristic of a systematic review such as reporting methodology, search terms, databases used, and inclusion and exclusion criteria [ 9 ]. With this in mind, our narrative review will give a detailed explanation of the important steps of a systematic review.

Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) checklist

Systematic reviews are conducted based on predefined criteria and protocol. The PRISMA-P checklist, developed by Moher, et al., contains 17 items (26 including sub-items) comprising the important steps of a systematic review, including information about authors, co-authors, their mailing and email addresses, affiliations, and any new or updated version of a previous systematic review [ 9 ]. It also identifies a plan for documenting important protocol amendments, registry names, registration numbers, financial disclosures, and other support services [ 10 ]. Moher, et al. also state that methods of systematic reviews involve developing eligibility criteria and describing information sources, search strategies, study selection processes, outcomes, assessment of bias in individual studies, and data synthesis [ 10 ].

Research question

Writing a research question is the first step in conducting a systematic review and is of paramount importance as it outlines both the need and validity of systematic reviews (Nguyen, et al., unpublished data). It also increases the efficiency of the review by limiting the time and cost of identifying and obtaining relevant literature [ 11 ]. The research question should summarize the main objective of a systematic review.

An example research question might read, “How does attention-deficit/hyperactivity disorder (ADHD) affect the academic performance of middle school children in North America?” The question focuses on the type of data, analysis, and topic to be discussed (i.e., ADHD among North American middle school students). Try to avoid research questions that are too narrow or broad—they can lead to the selection of only a few studies and the ability to generalize results to any other populations may be limited. An example of a research question that is too narrow would be, “What is the prevalence of ADHD in children and adolescents in Chicago, IL?” Alternately, if the research question is too broad, it can be difficult to reach a conclusion due to poor methodology. An example of a research question that is too broad in scope would be, “What are the effects of ADHD on the functioning of children and adolescents in North America?”

Different tools that can be used to help devise a research question, depending on the type of question, are: population, intervention, comparator, and outcomes (PICO); sample, phenomenon of interest, design, evaluation, and research type (SPIDER); setting, perspective, intervention, comparison, and evaluation (SPICE); and expectation, client group, location, impact, professionals, and service (ECLIPSE).

The PICO approach is mostly used to compare different interventions with each other. It helps to formulate a research question related to prognosis, diagnosis, and therapies [ 12 ].

Scenario: A 50-year-old white woman visited her psychiatrist with a diagnosis of major depressive disorder. She was prescribed fluoxetine, which she feels has been helpful. However, she experienced some unpleasant side effects of nausea and abdominal discomfort. She has recently been told by a friend about the use of St. John’s wort in treating depression and would like to try this in treating her current depression. (Formulating research questions, unpublished data).

In the above-mentioned scenario, the sample population is a 50-year-old female with major depressive disorder; the intervention is St. John’s wort; the comparison is fluoxetine; and the outcome would be efficacy and safety. In order to see the outcome of both efficacy and safety, we will compare the efficacy and safety of both St. John’s wort and fluoxetine in a sample population for treating depression. This scenario represents an example where we can apply the PICO approach to compare two interventions.

In contrast, the SPIDER approach is focused more on study design and samples rather than populations [ 13 ]. The SPIDER approach can be used in this research question: “What is the experience of psychiatry residents attending a transgender education?” The sample is psychiatry residents; the phenomenon of interest is transgender education; the design is a survey; the evaluation looks at the experience; and the research type is qualitative.

The SPICE approach can be used to evaluate the outcome of a service, intervention, or project [ 14 ]. The SPICE approach applies to the following research question: “In psychiatry clinics, does the combined use of selective serotonin reuptake inhibitor (SSRI) and psychotherapy reduce depression in an outpatient clinic versus SSRI therapy alone?” The setting is the psychiatry clinic; the perspective/population is the outpatient; the intervention is combined psychotherapy and SSRI; the comparison is SSRI alone; and the evaluation is reduced depression.

The ECLIPSE approach is useful for evaluating the outcome of a policy or service (Nguyen, et al., unpublished data). ECLIPSE can apply in the following research question: “How can a resident get access to medical records of patients admitted to inpatient from other hospitals?” The expectation is: “What are you looking to improve/change to increase access to medical records for patients admitted to inpatient?” The client group is the residents; the location is the inpatient setting; the impact would be the residents having easy access to medical records from other hospitals; and the professionals in this scenario would be those involved in improving the service experiences such as hospital administrators and IT staff.

Inclusion and exclusion criteria

Establishing inclusion and exclusion criteria come after formulating research questions. The concept of inclusion and exclusion of data in a systematic review provides a basis on which the reviewer draws valid and reliable conclusions regarding the effect of the intervention for the disorder under consideration [ 11 ]. Inclusions and exclusion are based on preset criteria for specific systematic review. It should be done before starting the literature search in order to minimize the possibility of bias.

Eligibility criteria provide the boundaries of the systematic review [ 15 ]. Participants, interventions, and comparison of a research question provide the basis for eligibility criteria [ 15 ]. The inclusion criteria should be able to identify the studies of interest and, if the inclusion criteria are too broad or too narrow, it can lead to an ineffective screening process.

Protocol registration

Developing and registering research protocol is another important step of conducting a systematic review. The research protocol ensures that a systematic review is carefully planned and explicitly documented before the review starts, thus promoting consistency in conduct for the review team and supporting the accountability, research integrity, and transparency of the eventually completed review [ 10 ]. PROSPERO and the Cochrane Database of Systematic Reviews are utilized for registering research protocols and research questions, and they check for prior existing duplicate protocols or research questions. PROSPERO is an international database of prospectively registered systematic reviews related to health care and social sciences (PRISMA, 2016). It is funded by the National Institute for Health Research. The Cochrane Collaboration concentrates on producing systematic reviews of interventions and diagnostic test accuracy but does not currently produce reviews on questions of prognosis or etiology [ 16 ].

A detailed and extensive search strategy is important for the systematic review since it minimizes bias in the review process [ 17 ].

Selecting and searching appropriate electronic databases is determined by the topic of interest. Important databases are: MEDLARS Online (MEDLINE), which is the online counterpart to the Medical Literature Analysis and Retrieval System (MEDLARS); Excerpta Medica Database (EMBASE); and Google Scholar. There are multiple electronic databases available based on the area of interest. Other important databases include: PsycINFO for psychology and psychiatry; Allied and Complementary Medicine Database (AMED) for complementary medicine; Manual, Alternative, and Natural Therapy Index System (MANTIS) for alternative medical literature; and Cumulative Index to Nursing and Allied Health Literature (CINAHL) for nursing and allied health [ 15 ].

Additional studies relevant for the review may be found by looking at the references of studies identified by different databases [ 15 ]. Non-indexed articles may be found by searching the content of journals, conferences proceedings, and abstracts. It will also help with letters and commentaries which may not get indexed [ 15 ]. Reviewing clinical trial registries can provide information about any ongoing trials or unpublished research [ 15 ]. A gray literature search can access unpublished papers, reports, and conference reports, and it generally covers studies that are published in an informal fashion, rather than in an indexed journal [ 15 ]. Further search can be performed by selecting important key articles and going through in-text citations [ 15 ].

Using Boolean operators, truncation, and wildcards

Boolean operators use the relationship between different search words to help with the search strategy. These are simple words (i.e., AND, OR, and NOT) which can help with more focused and productive results (poster, Jahan, et al.: How to conduct a systematic review. APPNA 39th Summer Convention. Washington, DC. 2016). The Boolean operator AND finds articles with all the search words. The use of OR broadens the focus of the search, and it will include articles with at least one search term. The researchers can also ignore certain results from the records by using NOT in the search strategy.

An example of AND would be using “depression” AND “children” in the search strategy with the goal of studying depression in children. This search strategy will include all the articles about both depression and children. The researchers may use OR if the emphasis of the study is mood disorders or affective disorders in adolescents. In that case, the search strategy will be “mood disorders” OR “affective disorders” AND “adolescents.” This search will find all the articles about mood disorders or affective disorders in adolescents. The researchers can use NOT if they only want to study depression in children and want to ignore bipolar disorder from the search. An example search in this scenario would be “depression” NOT “bipolar disorder” AND “children.” This will help ignore studies related to bipolar disorder in children.

Truncation and wildcards are other tools to make search strategy more comprehensive and focused. While the researchers search a database for certain articles, they frequently face terminologies that have the same initial root of a word but different endings. An example would be "autism," "autistic," and "autism spectrum disorder." These words have a similar initial root derived from “autis” but they end differently in each case. The truncation symbol (*) retrieves articles that contain words beginning with “autis” plus any additional characters. Wildcards are used for words with the same meanings but different spellings due to various reasons. For the words with spelling variations of a single letter, wildcard symbols can be used. When the researcher inputs “M+N” in the search bar, this returns results containing both “man” or “men” as the wildcard accounts for the spelling variations between the letters M and N.

Study selection

Study selection should be performed in a systematic manner, so reviewers deal with fewer errors and a lower risk of bias (online course, Li T, Dickersin K: Introduction to systematic review and meta-analysis. 2016. https://www.coursera.org/learn/systematic-review #). Study selection should involve two independent reviewers who select studies using inclusion and exclusion criteria. Any disagreements during this process should be resolved by discussion or by a third reviewer [ 10 ]. Specific study types can be selected depending on the research question. For example, questions on incidence and prevalence can be answered by surveys and cohort studies. Clinical trials can provide answers to questions related to therapy and screening. Queries regarding diagnostic accuracy can be answered by clinical trials and cross-sectional studies (online course, Li T, Dickersin K: Introduction to systematic review and meta-analysis. 2016. https://www.coursera.org/learn/systematic-review #). Prognosis and harm-related questions should use cohort studies and clinical trials, and etiology questions should use case-control and cohort studies (online course, Li T, Dickersin K: Introduction to systematic review and meta-analysis. 2016. https://www.coursera.org/learn/systematic-review #).

Data screening and data extractions are two of the major steps in conducting a systematic review [ 18 ]. Data screening involves searching for relevant articles in different databases using keywords. The next step of data screening is manuscript selection by reviewing each manuscript in the search results to compare that manuscript against the inclusion criteria [ 18 ]. The researchers should also review the references of the papers selected before selecting the final paper, which is the last step of data screening [ 18 ].

The next stage is extracting and appraising the data of the included articles [ 18 ]. A data extraction form should be used to help reduce the number of errors, and more than one person should record the data [ 17 ]. Data should be collected on specific points like population type, study authors, agency, study design, humanitarian crisis, target age groups, research strengths from the literature, setting, study country, type(s) of public health intervention, and health outcome(s) addressed by the public health intervention. All this information should then be put into an electronic database [ 18 ].

Assessing bias

Bias is a systematic error (or deviation from the truth) in results or inferences. Biases can change the results of any study and lead to an underestimation or overestimation of the true intervention effect [ 19 ]. Biases can impact any aspect of a review, including selecting studies, collecting and extracting data, and making a conclusion. Biases can vary in magnitude; some are small, with negligible effect, but some are substantial to a degree where an apparent finding may be entirely due to bias [ 19 ]. There are different types of bias, including, but not limited to, selection, detection, attrition, reporting, and performance.

Selection bias occurs when a sample selected is not representative of the whole general population. If randomization of the sample is done correctly, then chances of selection bias can be minimized [ 20 ].

Detection bias refers to systematic differences between groups in how outcomes are determined. This type of bias is based on knowledge of the intervention provided and its outcome [ 19 ].

Attrition bias refers to systematic differences between groups in withdrawals from a study [ 19 ]. The data will be considered incomplete if some subjects are withdrawn or have irregular visits during data collection.

Reporting bias refers to systematic differences between reported and unreported findings, and it is commonly seen during article reviews. Reporting bias is based on reviewer judgment about the outcome of selected articles [ 20 ].

Performance bias develops due to the knowledge of the allocated interventions by participants and personnel during the study [ 20 ]. Using a double-blind study design helps prevent performance bias, where neither the experimenter nor the subjects know which group contains controls and which group contains the test article [ 14 ].

Last step of systematic review: discussion

The discussion of a systematic review is where a summary of the available evidence for different outcomes is written and discussed [ 10 ]. The limitations of a systematic review are also discussed in detail. Finally, a conclusion is drawn after evaluating the results and considering limitations [ 10 ].

Discussion of the current article

Systematic reviews with or without a meta-analysis are currently ranked to be the best available evidence in the hierarchy of evidence-based practice [ 21 ]. We have discussed the methodology of a systematic review. A systematic review is classified in the category of filtered information because it appraises the quality of the study and its application in the field of medicine [ 21 ]. However, there are some limitations of the systematic review, as we mentioned earlier in our article. A large randomized controlled trial may provide a better conclusion than a systematic review of many smaller trials due to their larger sample sizes [ 22 ], which help the researchers generalize their conclusions for a bigger population. Other important factors to consider include higher dropout rates in large studies, co-interventions, and heterogeneity among studies included in the review.

As we discussed the limitations of the systematic review and its effect on quality of evidence, there are several tools to rate the evidence, such as the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system [ 22 ]. GRADE provides a structured approach to evaluating the risk of bias, serious inconsistency between studies, indirectness, imprecision of the results, and publication bias [ 22 ]. Another approach used to rate the quality of evidence is a measurement tool to assess systematic reviews (AMSTAR) [ 23 ]. It is also available in several languages [ 23 ].

Conclusions

Despite its limitations, a systematic review can add to the knowledge of the scientific community especially when there are gaps in the existing knowledge. However, conducting a systematic review requires different steps that involve different tools and strategies. It can be difficult at times to access and utilize these resources. A researcher can understand and strategize a systematic review following the different steps outlined in this literature review. However, conducting a systematic review requires a thorough understanding of all the concepts and tools involved, which is an extensive endeavor to be summed up in one article.

The Cochrane Handbook for Systematic Reviews of Interventions and the Center for Reviews and Dissemination (CRD) provide excellent guidance through their insightful and detailed guidelines. We recommend consulting these resources for further guidance.

Given that our article is a narrative review of the scholarly literature, it contains the same limitations as noted for any narrative review. We hope that our review of the means and methods for conducting a systematic review will be helpful in providing basic knowledge to utilize the resources available to the scientific community.

The content published in Cureus is the result of clinical experience and/or research by independent individuals or organizations. Cureus is not responsible for the scientific accuracy or reliability of data or conclusions published herein. All content published within Cureus is intended only for educational, research and reference purposes. Additionally, articles published within Cureus should not be deemed a suitable substitute for the advice of a qualified health care professional. Do not disregard or avoid professional medical advice due to content published within Cureus.

The authors have declared that no competing interests exist.

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Systematic literature reviews: Expert searchers can help avoid errors
Creative learning environments in education—A systematic literature review
Systematic literature review X narrative review
Differences between systematic and narrative reviews
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(PDF) Systematic literature review X narrative review

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Systematic Literature Review
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Narrative Review
Reviews: From Systematic to Narrative: Narrative Review The Narrative Review At its most basic, narrative reviews are most useful for obtaining a broad perspective on a topic and are often more comparable to a textbook chapter including sections on the physiology and/or epidemiology of a topic.
The Difference Between Narrative Review and Systematic Review
The main objective of a systematic review is to formulate a well-defined research question and use qualitative and quantitative methods to analyze all the available evidence attempting to answer the question. In contrast, narrative reviews can address one or more questions with a much broader scope.
Reviews: From Systematic to Narrative: Introduction
Most reviews fall into the following types: literature review, narrative review, integrative review, evidenced based review, meta-analysis and systematic review. This LibGuide will provide you a general overview of the specific review, offer starting points, and outline the reporting process.
How to Conduct a Systematic Review: A Narrative Literature Review
How to Conduct a Systematic Review: A Narrative Literature Review Authors Nusrat Jahan 1 , Sadiq Naveed 2 , Muhammad Zeshan 3 , Muhammad A Tahir 4 Affiliations 1 Psychiatry, Mount Sinai Chicago. 2 Psychiatry, KVC Prairie Ridge Hospital. 3 Department of Psychiatry, Bronx Lebanon Hospital Icahn School of Medicine at Mount Sinai, Bronx, NY.
Systematic reviews versus narrative reviews in clinical anatomy
Systematic reviews are overviews of the literature undertaken by identifying, critically appraising and synthesizing the results of primary research studies using an explicit methodological approach. With the recent rise of evidence-based anatomy, important questions arise with respect to the utility of narrative reviews in clinical anatomy.
(PDF) Systematic literature review X narrative review
A systematic literature review is a well-planned review to answer specific research questions using an organised and explicit methodology to identify, select, and critically evaluate the...
Why Systematic Review rather than Narrative Review?
Of course, there should be Pros and Cons between systematic and narrative reviews; for instance, the major advantage of systematic reviews is that they are based on the findings of comprehensive and systematic literature searches in all available resources, with minimization of selection bias avoiding subjective selection bias, while narrative …
How to Conduct a Systematic Review: A Narrative Literature Review
Narrative reviews take a less formal approach than systematic reviews in that narrative reviews do not require the presentation of the more rigorous aspects characteristic of a systematic review such as reporting methodology, search terms, databases used, and inclusion and exclusion criteria [9].
Literature Review vs Systematic Review
It's common to confuse systematic and literature reviews because both are used to provide a summary of the existent literature or research on a specific topic. Regardless of this commonality, both types of review vary significantly.
Systematic literature review X narrative review
Systematic literature review X narrative review. Acta Paulista de Enfermagem. ISSN 1982-0194. EN; PT; Home; About . About Acta Editorial Policy Editorial Board Editorial Responsibilities. ... Systematic literature review X narrative review. Acta Paul Enferm. [online]. 2007, vol. 20, n. 2, [cited 2023-02-27], pp.v-vi. Available from: <https ...
Systematic literature review X narrative review
DOI: 10.1590/S0103-21002007000200001 Corpus ID: 116849838; Systematic literature review X narrative review @article{Rother2007SystematicLR, title={Systematic literature review X narrative review}, author={Edna Terezinha Rother}, journal={Acta Paulista De Enfermagem}, year={2007}, volume={20} }
Main differences between narrative and systematic reviews
Narrative reviews, also referred to as literature reviews, are a method used to identify and consolidate that which has been previously published on a specific topic; this consolidation...
PDF STARTING A NARRATIVE SYNTHESIS
Guidelines are available to help review authors to structure narrative syntheses of results in systematic reviews.2 These outline several steps that can help review authors to systematically analyse and then integrate the results across ... 2 A copy of the guidelines (Popay et al (2006) Guidance on the conduct of narrative synthesis in ...
Types of Reviews
Systematic Reviews Review Typologies There are many types of evidence synthesis projects, including systematic reviews as well as others. The selection of review type is wholly dependent on the research question. Not all research questions are well-suited for systematic reviews. Review Typologies (from LITR-EX)
Research Guides: Systematic Reviews: Types of Literature Reviews
Qualitative, narrative synthesis. Thematic analysis, may include conceptual models. Rapid review. Assessment of what is already known about a policy or practice issue, by using systematic review methods to search and critically appraise existing research. Completeness of searching determined by time constraints.
Systematic Reviews & Other Review Types
A systematic review is defined as "a review of the evidence on a clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant primary research, and to extract and analyze data from the studies that are included in the review.". The methods used must be reproducible and transparent.
Depression and Its Phytopharmacotherapy—A Narrative Review
This narrative review results from a traditional, non-systematic literature review. It briefly discusses the pathophysiology, symptomatology and treatment of depression, with a particular focus on the role of phytopharmacology in its treatment. It provides the mechanisms of action revealed in experimental studies of active ingredients isolated ...
Narrative vs systematic vs scoping review: What's the difference?
This video elaborates on the difference between systematic and scoping reviews. A narrative review, also referred to as a traditional review, summarises and presents the available research on a topic. You will commonly see a traditional or narrative review as part of a thesis or dissertation.
What is the difference between a narrative review and a descriptive
However, at the academic/scientific level, a 'narrative review' is actually a literature review and a 'descriptive review' is a systematic review. A literature review, as the name suggests, is a review of existing literature around a particular topic. It involves discussing and possibly even critiquing existing studies.
Systematic Review
A systematic review is a type of review that uses repeatable methods to find, select, and synthesize all available evidence. It answers a clearly formulated research question and explicitly states the methods used to arrive at the answer. Example: Systematic review
What is a Systematic Review?
A narrative review does not require a systematic search of the literature and does not require included studies to be assessed for risk or bias. According to Ferrari (2015), narrative (literature) reviews are helpful for exploring general topics or debates, addressing more than one question, and identifying knowledge gaps and areas for future ...
Narrative Synthesis
& Duffy, S. (2006). Guidance on the conduct of narrative synthesis in systematic reviews. A product from the ESRC methods programme Version, 1(1), b92. Full Text. Thomson H, Campbell M. "Narrative synthesis" of quantitative effect data in Cochrane reviews: Current issues and ways forward [Internet].
ERIC
Objectives: The goal of this systematic scoping review was to summarize and synthesize the literature on the use of physical and/or mixed-reality simulation in pre-service teacher training. Methods: A systematic scoping literature review combined with a textual narrative synthesis was undertaken.
The difference between a systematic review and a literature ...
The results of a systematic review can be presented in many ways and the choice will depend on factors such as the type of data. Some reviews use meta-analysis to produce a statistical summary of effect estimates. Other reviews use narrative synthesis to present a textual summary.. Covidence accelerates the screening, data extraction, and quality assessment stages of your systematic review.
National Center for Biotechnology Information
National Center for Biotechnology Information