systematic literature review disadvantages

Strengths and Weaknesses of Systematic Reviews

Automate every stage of your literature review to produce evidence-based research faster and more accurately.

Systematic reviews are considered credible sources since they are comprehensive, reproducible, and precise in stating the outcomes. The type of review system used and the approach taken depend on the goals and objectives of the research. To choose the best-suited review system, researchers must be aware of the strengths and weaknesses of each one.

Let us now look at the strengths and limitations of systematic reviews.

Strengths Of Systematic Reviews

Systematic reviews have become increasingly popular owing to their transparency, accuracy, replicability, and reduced risk of bias. Some of the main benefits of systematic reviews are;

Specificity

Researchers can answer specific research questions of high importance. For example, the efficacy of a particular drug in the treatment of an illness.

Explicit Methodology

A systematic review requires rigorous planning. Each stage of the review is predefined to the last detail. The research question is formulated using the PICO (population, intervention, comparison, and outcome) approach. A strict eligibility criteria is then established for inclusion and exclusion criteria for selecting the primary studies for the review. Every stage of the systematic review methodology is pre-specified to the last detail and made publicly available, even before starting the review process. This makes all the stages in the methodology transparent and reproducible.

Reliable And Accurate Results

The results of a systematic review are either analyzed qualitatively and presented as a textual narrative or quantitatively using statistical methods such as meta-analyses and numeric effect estimates. The quality of evidence or the confidence in effect estimates is calculated using the standardized GRADE approach.

Comprehensive And Exhaustive

A systematic review involves a thorough search of all the available data on a certain topic. It is exhaustive and considers every bit of evidence in synthesizing the outcome. Primary sources for the review are collected from databases and multiple sources, such as blogs from pharmaceutical companies, unpublished research directly from researchers, government reports, and conference proceedings. These are referred to as grey literature. The search criteria and keywords used in sourcing are specific and predefined.

Reproducible

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Weaknesses Of Systematic Reviews

Although systematic reviews are robust tools in scientific research they are not immune to errors. They can be misleading, or even harmful if the data is inappropriately handled or if they are biased. Some of the limitations of systematic reviews include:

Mass Production

Due to the popularity systematic reviews have gained, they tend to be used more than required. The growth rate of systematic reviews has outpaced the growth rate of studies overall. This results in redundancy. For example, a survey published in the BMJ[1], included 73 randomly selected meta-analyses published in 2010 found that for two-thirds of these studies, there was at least one, and sometimes as many as 13, additional meta-analyses published on the same topic by early 2013.

Risk of Bias

Although systematic reviews have many advantages, they are also more susceptible to certain types of biases. A bias is a systematic or methodological error that causes misrepresentation of the study outcomes. As bias can appear at any stage, authors should be aware of the specific risks at each stage of the review process. Most of the known errors in systematic reviews arise in the selection and publication stages. The eligibility criterion in a systematic review helps to avoid selection bias. Poor study design and execution can also result in a biased outcome. It’s important to learn about the types of bias in systematic reviews .

Expressing Strong Opinions by Stealth

Selective outcome reporting is a major threat to a systematic review. The author or reviewer may decide to only report a selection of the statistically significant outcomes that suit his interest. The possibility of unfair or misleading interpretation of evidence outcomes in a systematic review can have serious implications.

Like any review system, systematic reviews have their advantages and disadvantages. Understanding them is essential to making a choice of which review system to use.

Overlapping meta-analyses on the same topic: survey of published studies. BMJ 2013; 347:f4501

3 Reasons to Connect

Eight problems with literature reviews and how to fix them

Affiliations.

• 1 Mercator Research Institute on Climate Change and Global Commons, Berlin, Germany. [email protected].
• 2 Stockholm Environment Institute, Stockholm, Sweden. [email protected].
• 3 Africa Centre for Evidence, University of Johannesburg, Johannesburg, South Africa. [email protected].
• 4 College of Medicine and Health, Exeter University, Exeter, UK.
• 5 Department of Zoology, University of Cambridge, Cambridge, UK.
• 6 School of Biological Sciences, University of East Anglia, Norwich, UK.
• 7 Department of Biological Sciences, Royal Holloway University of London, Egham, UK.
• 8 Stockholm Environment Institute, Stockholm, Sweden.
• 9 Department of Zoology, University of Oxford, Oxford, UK.
• 10 Collaboration for Environmental Evidence, UK Centre, School of Natural Sciences, Bangor University, Bangor, UK.
• 11 Liljus ltd, London, UK.
• 12 Department of Forest Sciences, University of Helsinki, Helsinki, Finland.
• 13 Evidence Synthesis Lab, School of Natural and Environmental Sciences, University of Newcastle, Newcastle-upon-Tyne, UK.
• PMID: 33046871
• DOI: 10.1038/s41559-020-01295-x

Traditional approaches to reviewing literature may be susceptible to bias and result in incorrect decisions. This is of particular concern when reviews address policy- and practice-relevant questions. Systematic reviews have been introduced as a more rigorous approach to synthesizing evidence across studies; they rely on a suite of evidence-based methods aimed at maximizing rigour and minimizing susceptibility to bias. Despite the increasing popularity of systematic reviews in the environmental field, evidence synthesis methods continue to be poorly applied in practice, resulting in the publication of syntheses that are highly susceptible to bias. Recognizing the constraints that researchers can sometimes feel when attempting to plan, conduct and publish rigorous and comprehensive evidence syntheses, we aim here to identify major pitfalls in the conduct and reporting of systematic reviews, making use of recent examples from across the field. Adopting a 'critical friend' role in supporting would-be systematic reviews and avoiding individual responses to police use of the 'systematic review' label, we go on to identify methodological solutions to mitigate these pitfalls. We then highlight existing support available to avoid these issues and call on the entire community, including systematic review specialists, to work towards better evidence syntheses for better evidence and better decisions.

• Environment
• Research Design
• Systematic Reviews as Topic*

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Eight problems with literature reviews and how to fix them

• Neal R. Haddaway   ORCID: orcid.org/0000-0003-3902-2234 1 , 2 , 3 ,
• Alison Bethel 4 ,
• Lynn V. Dicks 5 , 6 ,
• Julia Koricheva   ORCID: orcid.org/0000-0002-9033-0171 7 ,
• Biljana Macura   ORCID: orcid.org/0000-0002-4253-1390 2 ,
• Gillian Petrokofsky 8 ,
• Andrew S. Pullin 9 ,
• Sini Savilaakso   ORCID: orcid.org/0000-0002-8514-8105 10 , 11 &
• Gavin B. Stewart   ORCID: orcid.org/0000-0001-5684-1544 12  

Nature Ecology & Evolution volume  4 ,  pages 1582–1589 ( 2020 ) Cite this article

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Traditional approaches to reviewing literature may be susceptible to bias and result in incorrect decisions. This is of particular concern when reviews address policy- and practice-relevant questions. Systematic reviews have been introduced as a more rigorous approach to synthesizing evidence across studies; they rely on a suite of evidence-based methods aimed at maximizing rigour and minimizing susceptibility to bias. Despite the increasing popularity of systematic reviews in the environmental field, evidence synthesis methods continue to be poorly applied in practice, resulting in the publication of syntheses that are highly susceptible to bias. Recognizing the constraints that researchers can sometimes feel when attempting to plan, conduct and publish rigorous and comprehensive evidence syntheses, we aim here to identify major pitfalls in the conduct and reporting of systematic reviews, making use of recent examples from across the field. Adopting a ‘critical friend’ role in supporting would-be systematic reviews and avoiding individual responses to police use of the ‘systematic review’ label, we go on to identify methodological solutions to mitigate these pitfalls. We then highlight existing support available to avoid these issues and call on the entire community, including systematic review specialists, to work towards better evidence syntheses for better evidence and better decisions.

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We thank C. Shortall from Rothamstead Research for useful discussions on the topic.

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Overview, Strengths, and Limitations of Systematic Reviews and Meta-Analyses

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While the main focus of this chapter will be meta-analysis, it cannot be completely isolated from several prerequisites assessed in the systematic review. For example, the studies must address a common question. The eligibility criteria of the underlying studies must be well established. Evaluation techniques for endpoints must be reasonably consistent across the studies. In the clinical setting, when making comparisons between a treatment and control, the underlying studies must be properly randomized. Exploratory meta-analyses and meta-regressions may examine associations between interventions, covariates, and secondary events.

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Bartolucci, A.A., Hillegass, W.B. (2010). Overview, Strengths, and Limitations of Systematic Reviews and Meta-Analyses. In: Chiappelli, F. (eds) Evidence-Based Practice: Toward Optimizing Clinical Outcomes. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-05025-1_2

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Neal Haddaway

October 19th, 2020, 8 common problems with literature reviews and how to fix them.

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Estimated reading time: 5 minutes

Literature reviews are an integral part of the process and communication of scientific research. Whilst systematic reviews have become regarded as the highest standard of evidence synthesis, many literature reviews fall short of these standards and may end up presenting biased or incorrect conclusions. In this post, Neal Haddaway highlights 8 common problems with literature review methods, provides examples for each and provides practical solutions for ways to mitigate them.

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Researchers regularly review the literature – it’s an integral part of day-to-day research: finding relevant research, reading and digesting the main findings, summarising across papers, and making conclusions about the evidence base as a whole. However, there is a fundamental difference between brief, narrative approaches to summarising a selection of studies and attempting to reliably and comprehensively summarise an evidence base to support decision-making in policy and practice.

So-called ‘evidence-informed decision-making’ (EIDM) relies on rigorous systematic approaches to synthesising the evidence. Systematic review has become the highest standard of evidence synthesis and is well established in the pipeline from research to practice in the field of health . Systematic reviews must include a suite of specifically designed methods for the conduct and reporting of all synthesis activities (planning, searching, screening, appraising, extracting data, qualitative/quantitative/mixed methods synthesis, writing; e.g. see the Cochrane Handbook ). The method has been widely adapted into other fields, including environment (the Collaboration for Environmental Evidence ) and social policy (the Campbell Collaboration ).

Despite the growing interest in systematic reviews, traditional approaches to reviewing the literature continue to persist in contemporary publications across disciplines. These reviews, some of which are incorrectly referred to as ‘systematic’ reviews, may be susceptible to bias and as a result, may end up providing incorrect conclusions. This is of particular concern when reviews address key policy- and practice- relevant questions, such as the ongoing COVID-19 pandemic or climate change.

These limitations with traditional literature review approaches could be improved relatively easily with a few key procedures; some of them not prohibitively costly in terms of skill, time or resources.

In our recent paper in Nature Ecology and Evolution , we highlight 8 common problems with traditional literature review methods, provide examples for each from the field of environmental management and ecology, and provide practical solutions for ways to mitigate them.

There is a lack of awareness and appreciation of the methods needed to ensure systematic reviews are as free from bias and as reliable as possible: demonstrated by recent, flawed, high-profile reviews. We call on review authors to conduct more rigorous reviews, on editors and peer-reviewers to gate-keep more strictly, and the community of methodologists to better support the broader research community. Only by working together can we build and maintain a strong system of rigorous, evidence-informed decision-making in conservation and environmental management.

Note: This article gives the views of the authors, and not the position of the LSE Impact Blog, nor of the London School of Economics. Please review our  comments policy  if you have any concerns on posting a comment below

Image credit:  Jaeyoung Geoffrey Kang  via unsplash

About the author

Neal Haddaway is a Senior Research Fellow at the Stockholm Environment Institute, a Humboldt Research Fellow at the Mercator Research Institute on Global Commons and Climate Change, and a Research Associate at the Africa Centre for Evidence. He researches evidence synthesis methodology and conducts systematic reviews and maps in the field of sustainability and environmental science. His main research interests focus on improving the transparency, efficiency and reliability of evidence synthesis as a methodology and supporting evidence synthesis in resource constrained contexts. He co-founded and coordinates the Evidence Synthesis Hackathon (www.eshackathon.org) and is the leader of the Collaboration for Environmental Evidence centre at SEI. @nealhaddaway

Why is mission creep a problem and not a legitimate response to an unexpected finding in the literature? Surely the crucial points are that the review’s scope is stated clearly and implemented rigorously, not when the scope was finalised.

• Pingback: Quick, but not dirty – Can rapid evidence reviews reliably inform policy? | Impact of Social Sciences

#9. Most of them are terribly boring. Which is why I teach students how to make them engaging…and useful.

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Advantages and disadvantages of literature review

This comprehensive article explores some of the advantages and disadvantages of literature review in research. Reviewing relevant literature is a key area in research, and indeed, it is a research activity in itself. It helps researchers investigate a particular topic in detail. However, it has some limitations as well.

What is literature review?

In order to understand the advantages and disadvantages of literature review, it is important to understand what a literature review is and how it differs from other methods of research. According to Jones and Gratton (2009) a literature review essentially consists of critically reading, evaluating, and organising existing literature on a topic to assess the state of knowledge in the area. It is sometimes called critical review.

A literature review is a select analysis of existing research which is relevant to a researcher’s selected topic, showing how it relates to their investigation. It explains and justifies how their investigation may help answer some of the questions or gaps in the chosen area of study (University of Reading, 2022).

A literature review is a term used in the field of research to describe a systematic and methodical investigation of the relevant literature on a particular topic. In other words, it is an analysis of existing research on a topic in order to identify any relevant studies and draw conclusions about the topic.

A literature review is not the same as a bibliography or a database search. Rather than simply listing references to sources of information, a literature review involves critically evaluating and summarizing existing research on a topic. As such, it is a much more detailed and complex process than simply searching databases and websites, and it requires a lot of effort and skills.

Advantages of literature review

Information synthesis

A literature review is a very thorough and methodical exercise. It can be used to synthesize information and draw conclusions about a particular topic. Through a careful evaluation and critical summarization, researchers can draw a clear and comprehensive picture of the chosen topic.

Familiarity with the current knowledge

According to the University of Illinois (2022), literature reviews allow researchers to gain familiarity with the existing knowledge in their selected field, as well as the boundaries and limitations of that field.

Creation of new body of knowledge

One of the key advantages of literature review is that it creates new body of knowledge. Through careful evaluation and critical summarisation, researchers can create a new body of knowledge and enrich the field of study.

Answers to a range of questions

Literature reviews help researchers analyse the existing body of knowledge to determine the answers to a range of questions concerning a particular subject.

Disadvantages of literature review

Time consuming

As a literature review involves collecting and evaluating research and summarizing the findings, it requires a significant amount of time. To conduct a comprehensive review, researchers need to read many different articles and analyse a lot of data. This means that their review will take a long time to complete.

Lack of quality sources  

Researchers are expected to use a wide variety of sources of information to present a comprehensive review. However, it may sometimes be challenging for them to identify the quality sources because of the availability of huge numbers in their chosen field. It may also happen because of the lack of past empirical work, particularly if the selected topic is an unpopular one.

Descriptive writing

One of the major disadvantages of literature review is that instead of critical appreciation, some researchers end up developing reviews that are mostly descriptive. Their reviews are often more like summaries of the work of other writers and lack in criticality. It is worth noting that they must go beyond describing the literature.

Key features of literature review

Clear organisation

A literature review is typically a very critical and thorough process. Universities usually recommend students a particular structure to develop their reviews. Like all other academic writings, a review starts with an introduction and ends with a conclusion. Between the beginning and the end, researchers present the main body of the review containing the critical discussion of sources.

No obvious bias

A key feature of a literature review is that it should be very unbiased and objective. However, it should be mentioned that researchers may sometimes be influenced by their own opinions of the world.

Proper citation

One of the key features of literature review is that it must be properly cited. Researchers should include all the sources that they have used for information. They must do citations and provide a reference list by the end in line with a recognized referencing system such as Harvard.

To conclude this article, it can be said that a literature review is a type of research that seeks to examine and summarise existing research on a particular topic. It is an essential part of a dissertation/thesis. However, it is not an easy thing to handle by an inexperienced person. It also requires a lot of time and patience.

Hope you like this ‘Advantages and disadvantages of literature review’. Please share this with others to support our research work.

Other useful articles:

How to evaluate website content

Advantages and disadvantages of primary and secondary research

Advantages and disadvantages of simple random sampling

Last update: 08 May 2022

References:

Jones, I., & Gratton, C. (2009) Research Methods for Sports Shttps://www.howandwhat.net/new/evaluate-website-content/tudies, 2 nd edition, London: Routledge

University of Illinois (2022) Literature review, available at: https://www.uis.edu/learning-hub/writing-resources/handouts/learning-hub/literature-review (accessed 08 May 2022)

University of Reading (2022) Literature reviews, available at: https://libguides.reading.ac.uk/literaturereview/starting (accessed 07 May 2022)

Author: M Rahman

M Rahman writes extensively online and offline with an emphasis on business management, marketing, and tourism. He is a lecturer in Management and Marketing. He holds an MSc in Tourism & Hospitality from the University of Sunderland. Also, graduated from Leeds Metropolitan University with a BA in Business & Management Studies and completed a DTLLS (Diploma in Teaching in the Life-Long Learning Sector) from London South Bank University.

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Why Systematic Review rather than Narrative Review?

1 Department of Psychiatry, The Catholic University of Korea College of Medicine, Seoul, Republic of Korea.

2 Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA.

Sir: Recently review articles including systematic and narrative reviews have been significantly increasing in most psychiatric journals in the world alongside "Psychiatry Investigation (PI)". Since the launch of the "PI" at March 2004, there have been a number of review articles; indeed 54 papers were published as format of regular review papers or special articles in the "PI" from 2004 to 2014. However, of the 54 papers, only one review paper partially met the contemporary criteria of systematic review, otherwise were written as a format of narrative review for diverse topics such as epidemiological findings, concept and hypothesis of certain psychiatric disease, current understandings on certain disease, psychopharmacology, and treatment guidelines. This is unsatisfactory when reflecting the fact that systematic reviews have been rapidly and increasingly replacing traditional narrative (explicit) reviews as a standard platform of providing and updating currently available research findings as confident evidence. Most journals have started to change their policy in acceptance of review papers, they have been giving a priority to systematic review only as a regular review article and excluding narrative reviews, to provide the best evidence for all basic and clinical questions and further hypotheses. 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 reviews, if they can be written experts in certain research area, can provide experts' intuitive, experiential and explicit perspectives in focused topics. 1

The absence of objective and systematic selection criteria in review method substantially results in a number of methodological shortcomings leading to clear bias of the author's interpretation and conclusions. Such differences are quite clear when referring to the review paper of Drs. Cipriani and Geddess, 2 where 7 narrative and 2 systematic reviews were compared and found that narrative reviews including same studies reached different conclusions against each other, indicating the difficulties of appraising and using narrative reviews to have conclusion on specific topic. Hence, narrative reviews may be evidence-based, but they are not truly useful as scientific evidence.

Even in reported as systematic review, it is also frequent that those papers are not true systematic review or they have certain bias in data search method and conclusions. For instance, due to lack of satisfactory pharmacotherapy for post-traumatic stress disorder (PTSD) and its frequent comorbid psychotic symptoms, a possible role of atypical antipsychotics (AAs) for PTSD has been consistently proposed. 3 In fact various AAs have demonstrated positive antidepressant and ant-anxiety effects in a number of small-scale, open-label studies (OLSs) or randomised, controlled clinical trials (RCTs). 4 In this context, a recent systematic review (4 olanzapine, 7 risperidone and 1 ziprasidone trials) by Wang et al. 5 has also suggested the positive prospect on the role of AAs for the treatment of PTSD; however, the review has a number of faulty and wrong selection of clinical trials data and interpretation of studies included in their review. The authors neglected wide range of clinical information such as patient characteristics (particularly, initial severity of disease), comorbidity issues, trial duration issues, trial design characteristics, primary endpoint difference, study sponsoring; that is, heterogeneity of clinical trials would substantially influence the quality and clinical implications of the study results. The basic problem of non-systematic search of data is that beneath the shining surface, it seems that the authors utilizing it often misunderstand the true value, underpinning meanings and correct nature of the data, or their true limitations and strengths, and they often go too far or short with the interpretation. 6 Indeed, the main conclusion of a narrative review may often be based on evidence, but such reviews themselves are not rigorous evidence since such reviews are too selective and thus little good quality information could be included. 2 In addition, I found one olanzapine trial was OLS but they included the study in the result (this is a mixture of data yielding a huge heterogeneity). 7 This clearly indicates they were not consistent in collection of the study for their review. Olanzapine has a lot of OLSs beyond the study, likewise other AAs also have a plenty of OLSs. Regarding an inclusion of OLSs for systematic reviews, an interesting metaanalyses are available on the role of olanzapine for adolescent bipolar disorder 8 and aripiprazole augmentation therapy 9 for depression. According to Pae et al. 9 the treatment effects were not significantly different between OLSs and RCTs in efficacy of aripiprazole augmentation for treating depression; the pooled effect size was statistically significant in both study design and also in a meta-analysis regression, study design was not a significant predictor of mean change in the primary endpoint, clearly indicating that OLSs are useful predictors of the potential safety and efficacy of a given compound. This finding was also supported by another meta-analysis. 8 Hence, the value of OLSs should be carefully re-evaluated for practical information source, development of new drugs or acquisition for new indications, and should not be neglected for data research, especially for narrative reviews. Furthermore, Dr. Wang et al. 5 did not include one important RCT; quetiapine has a RCT for PTSD, 10 which was presented in the thematic meeting of the CINP 2009. A 12-week RCT was conducted for 80 PTSD patients. Finally, Wang et al. 5 surprisingly did not present any effect size (ES) for studies, although such calculations are conventionally included in the review papers. Another critical example is Hickie and Rogers's review, 11 according to their article, agomelatine was efficacious antidepressant; however, subsequent researchers who avoided selection bias have clearly demonstrated its weak efficacy as an antidepressant. 12 Therefore, reflecting two review papers, 5 , 11 we can realize that inappropriate aggregation of studies may definitely bias conclusion. Hence, entire published and unpublished dataset should be considered in systematic review, especially, when clinical data is not sufficient and the medication has no officially approved indication by the regulatory agency.

To summarize, systematic review should include followings respecting recommendation from currently available systematic review guidelines (e.g., The Cochrane Library www.cochrane.org ); clear basic and clinical hypothesis, predefined protocol, designation of search resources, through data search (regardless of publication), transparent selection criteria, qualification of studies selected, synthesis of study data and information, relevant summary and conclusion. Table 1 compares systematic and narrative reviews ( Table 1 ). Since the evidence-based medicine is the current trend and also mandatory for establishment of heath policy, the PI should also turn to encourage submission of systematic reviews rather than narrative reviews.

Acknowledgments

This work was supported by a grant of the Korean Health Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (HI12C0003).