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Systematic review

From HandWiki
Short description: Comprehensive review of research literature using systematic methods
A systematic review is the highest form of knowledge in science

A systematic review is a scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic.[1] A systematic review extracts and interprets data from published studies on the topic, then analyzes, describes, and summarizes interpretations into a refined conclusion.[1][2] For example, a systematic review of randomized controlled trials is a way of summarizing and implementing evidence-based medicine.[3]

While a systematic review may be applied in the biomedical or health care context, it may also be used where an assessment of a precisely defined subject can advance understanding in a field of research.[4] A systematic review may examine clinical tests, public health interventions, environmental interventions,[5] social interventions, adverse effects, qualitative evidence syntheses, methodological reviews, policy reviews, and economic evaluations.[6][7]

An understanding of systematic reviews and how to implement them in practice is common for professionals in health care, public health, and public policy.[1]


A systematic review can be designed to provide a thorough summary of current literature relevant to a research question.[1] A systematic review uses a rigorous and transparent approach for research synthesis, with the aim of assessing and, where possible, minimizing bias in the findings. While many systematic reviews are based on an explicit quantitative meta-analysis of available data, there are also qualitative reviews and other types of mixed-methods reviews which adhere to standards for gathering, analyzing and reporting evidence.[8]

Systematic reviews of quantitative data or mixed-method reviews sometimes use statistical techniques (meta-analysis) to combine results of eligible studies. Scoring levels are sometimes used to rate the quality of the evidence depending on the methodology used, although this is discouraged by the Cochrane Library.[9] As evidence rating can be subjective, multiple people may be consulted to resolve any scoring differences between how evidence is rated.[10][11][12]

The EPPI-Centre, Cochrane and the Joanna Briggs Institute have all been influential in developing methods for combining both qualitative and quantitative research in systematic reviews.[13][14][15] Several reporting guidelines exist to standardise reporting about how systematic reviews are conducted. Such reporting guidelines are not quality assessment or appraisal tools. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement[16] suggests a standardized way to ensure a transparent and complete reporting of systematic reviews, and is now required for this kind of research by more than 170 medical journals worldwide.[17] Several specialized PRISMA guideline extensions have been developed to support particular types of studies or aspects of the review process, including PRISMA-P for review protocols and PRISMA-ScR for scoping reviews.[17] A list of PRISMA guideline extensions is hosted by the EQUATOR (Enhancing the QUAlity and Transparency Of health Research) Network.[18]

For qualitative reviews, reporting guidelines include ENTREQ (Enhancing transparency in reporting the synthesis of qualitative research) for qualitative evidence syntheses; RAMESES (Realist And MEta-narrative Evidence Syntheses: Evolving Standards) for meta-narrative and realist reviews;[19][20] and eMERGe (Improving reporting of Meta-Ethnography) for meta-ethnograph.[13]

Developments in systematic reviews during the 21st century included realist reviews and the meta-narrative approach, both of which addressed problems of variation in methods and heterogeneity existing on some subjects.[21][22]


There are over 30 types of systematic review and Table 1 below summarises some of these, but it is not exhaustive.[17][16] It is important to note that there is not always consensus on the boundaries and distinctions between the approaches described below.

Table 1: A summary of some of the types of systematic review
Review type Summary
Mapping review/systematic map A mapping review maps existing literature and categorizes data. The method characterizes quantity and quality of literature, including by study design and other features. Mapping reviews can be used to identify the need for primary or secondary research.[17]
Meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple quantitative studies. Using statistical methods, results are combined to provide evidence from multiple studies. The two types of data generally used for meta-analysis in health research are individual participant data and aggregate data (such as odds ratios or relative risks).
Mixed studies review/mixed methods review Refers to any combination of methods where one significant stage is a literature review (often systematic). It can also refer to a combination of review approaches such as combining quantitative with qualitative research.[17]
Qualitative systematic review/qualitative evidence synthesis This method for integrates or compares findings from qualitative studies. The method can include 'coding' the data and looking for 'themes' or 'constructs' across studies. Multiple authors may improve the 'validity' of the data by potentially reducing individual bias.[17]
Rapid review An assessment of what is already known about a policy or practice issue, which uses systematic review methods to search for and critically appraise existing research. Rapid reviews are still a systematic review, however parts of the process may be simplified or omitted in order to increase rapidity.[23] Rapid reviews were used during the COVID-19 pandemic.[24]
Systematic review A systematic search for data, using a repeatable method. It includes appraising the data (for example the quality of the data) and a synthesis of research data.
Systematic search and review Combines methods from a 'critical review' with a comprehensive search process. This review type is usually used to address broad questions to produce the most appropriate evidence synthesis. This method may or may not include quality assessment of data sources.[17]
Systematized review Include elements of systematic review process, but searching is often not as comprehensive as a systematic review and may not include quality assessments of data sources.

Scoping reviews

Scoping reviews are distinct from systematic reviews in several important ways. A scoping review is an attempt to search for concepts by mapping the language and data which surrounds those concepts and adjusting the search method iteratively to synthesize evidence and assess the scope of an area of inquiry.[21][22] This can mean that the concept search and method (including data extraction, organisation and analysis) are refined throughout the process, sometimes requiring deviations from any protocol or original research plan.[25][26] A scoping review may often be a preliminary stage before a systematic review, which 'scopes' out an area of inquiry and maps the language and key concepts to determine if a systematic review is possible or appropriate, or to lay the groundwork for a full systematic review. The goal can be to assess how much data or evidence is available regarding a certain area of interest.[25][27] This process is further complicated if it is mapping concepts across multiple languages or cultures.

As a scoping review should be systematically conducted and reported (with a transparent and repeatable method), some academic publishers categorize them as a kind of 'systematic review', which may cause confusion. Scoping reviews are helpful when it is not possible to carry out a systematic synthesis of research findings, for example, when there are no published clinical trials in the area of inquiry. Scoping reviews are helpful when determining if it is possible or appropriate to carry out a systematic review, and are a useful method when an area of inquiry is very broad,[28] for example, exploring how the public are involved in all stages systematic reviews.[29]

There is still a lack of clarity when defining the exact method of a scoping review as it is both an iterative process and is still relatively new.[30] There have been several attempts to improve the standardisation of the method,[26][25][27][31] for example via a PRISMA guideline extension for scoping reviews (PRISMA-ScR).[32] PROSPERO (the International Prospective Register of Systematic Reviews) does not permit the submission of protocols of scoping reviews,[33] although some journals will publish protocols for scoping reviews.[29]


While there are multiple kinds of systematic review methods, the main stages of a review can be summarised as follows:

Defining the research question

Defining an answerable question and agreeing an objective method is required to design a useful systematic review.[34] Best practice recommends publishing the protocol of the review before initiating it to reduce the risk of unplanned research duplication and to enable transparency, and consistency between methodology and protocol.[35] Clinical reviews of quantitative data are often structured using the acronym PICO, which stands for 'Population or Problem', 'Intervention or Exposure', 'Comparison' and 'Outcome', with other variations existing for other kinds of research. For qualitative reviews PICo is 'Population or Problem', 'Interest' and 'Context'.

Searching for relevant data sources

Planning how the review will search for relevant data from research that matches certain criteria is a decisive stage in developing a rigorous systematic review. Relevant criteria can include only selecting research that is good quality and answers the defined question.[34] The search strategy should be designed to retrieve literature that matches the protocol's specified inclusion and exclusion criteria.

The methodology section of a systematic review should list all of the databases and citation indices that were searched. The titles and abstracts of identified articles can be checked against pre-determined criteria for eligibility and relevance. Each included study may be assigned an objective assessment of methodological quality, preferably by using methods conforming to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement,[18] or the high-quality standards of Cochrane.[36]

Common information sources used in searches include scholarly databases of peer-reviewed articles such as MEDLINE, Web of Science, Embase, and PubMed as well as sources of unpublished literature such as clinical trial registries and grey literature collections. Key references can also be yielded through additional methods such as citation searching, reference list checking (related to a search method called 'pearl growing'), manually searching information sources not indexed in the major electronic databases (sometimes called 'hand-searching'),[37] and directly contacting experts in the field.[38]

To be systematic, searchers must use a combination of search skills and tools such as database subject headings, keyword searching, Boolean operators, proximity searching, while attempting to balance the sensitivity (systematicity) and precision (accuracy). Inviting and involving an experienced information professional or librarian can notably improve the quality of systematic review search strategies and reporting.[39][40][41][42][43]

'Extraction' of relevant data

A visualisation of data being 'extracted' and 'combined' in a Cochrane intervention effect review where a meta-analysis is possible[44]

Relevant data are 'extracted' from the data sources according to the review method. It is important to note that the data extraction method is specific to the kind of data, and data extracted on 'outcomes' is only relevant to certain types of reviews. For example, a systematic review of clinical trials might extract data about how the research was done (often called the method or 'intervention'), who participated in the research (including how many people), how it was paid for (for example funding sources) and what happened (the outcomes).[34] Effectively, relevant data being extracted and 'combined' in a Cochrane intervention effect review, where a meta-analysis is possible.[44]

Assess the eligibility of the data

This stage involves assessing the eligibility of data for inclusion in the review, by judging it against criteria identified at the first stage.[34] This can include assessing if a data source meets the eligibility criteria, and recording why decisions about inclusion or exclusion in the review were made. Software can be used to support the selection process including text mining tools and machine learning, which can automate aspects of the process.[45] The 'Systematic Review Toolbox' is a community driven, web-based catalogue of tools, to help reviewers chose appropriate tools for reviews.[46]

Analyse and combine the data

Analysing and combining data can provide an overall result from all the data. Because this combined result may use qualitative or quantitative data from all eligible sources of data, it is considered more reliable as it provides better evidence, as the more data included in reviews, the more confident we can be of conclusions. When appropriate, some systematic reviews include a meta-analysis, which uses statistical methods to combine data from multiple sources. A review might use quantitative data, or might employ a qualitative meta-synthesis, which synthesises data from qualitative studies. A review may also bring together the findings from quantitative and qualitative studies in a mixed methods or overarching synthesis.[47] The combination of data from a meta-analysis can sometimes be visualised. One method uses a forest plot (also called a blobbogram).[34] In an intervention effect review, the diamond in the 'forest plot' represents the combined results of all the data included.[34]

An example of a 'forest plot' is the Cochrane Collaboration logo.[34] The logo is a forest plot of one of the first reviews which showed that corticosteroids given to women who are about to give birth prematurely can save the life of the newborn child.[48]

Recent visualisation innovations include the albatross plot, which plots p-values against sample sizes, with approximate effect-size contours superimposed to facilitate analysis.[49] The contours can be used to infer effect sizes from studies that have been analysed and reported in diverse ways. Such visualisations may have advantages over other types when reviewing complex interventions.

Assessing the quality (or certainty) of evidence is an important part of some reviews. GRADE (Grading of Recommendations, Assessment, Development and Evaluations) is a transparent framework for developing and presenting summaries of evidence and is used to grade the quality of evidence.[50] The GRADE-CERQual (Confidence in the Evidence from Reviews of Qualitative research) is used to provide a transparent method for assessing the confidence of evidence from reviews or qualitative research.[51]

Communication and dissemination

Once these stages are complete, the review may be published, disseminated and translated into practice after being adopted as evidence. The UK National Institute for Health Research (NIHR) defines dissemination as ‘getting the findings of research to the people who can make use of them to maximise the benefit of the research without delay’.[52] However, many evidence users do not have time to invest in reading large and complex documents and/or may lack awareness or be unable to access newly published research. Researchers are therefore developing skills to use creative communication methods such as illustrations, blogs, infographics and board games to share the findings of systematic reviews.[53]

Automation of systematic reviews

Living systematic reviews are a relatively new kind of high quality, semi-automated, up-to-date online summaries of research which are updated as new research becomes available.[54] The essential difference between a living systematic review and a conventional systematic review is the publication format. Living systematic reviews are 'dynamic, persistent, online-only evidence summaries, which are updated rapidly and frequently'.[55]

While living systematic reviews seek to maintain current evidence, the automation or semi-automation of the systematic process itself is increasingly being explored. While little evidence exists to demonstrate it is as accurate or involves less manual effort, efforts that promote training and using artificial intelligence for the process are increasing.[56][54]

Research fields

Medicine and human health

History of systematic reviews in medicine

A 1904 British Medical Journal paper by Karl Pearson collated data from several studies in the UK, India and South Africa of typhoid inoculation. He used a meta-analytic approach to aggregate the outcomes of multiple clinical studies.[57] In 1972 Archie Cochrane wrote: 'It is surely a great criticism of our profession that we have not organised a critical summary, by specialty or subspecialty, adapted periodically, of all relevant randomised controlled trials'.[58] Critical appraisal and synthesis of research findings in a systematic way emerged in 1975 under the term 'meta analysis'.[59][60] Early syntheses were conducted in broad areas of public policy and social interventions, with systematic research synthesis applied to medicine and health.[61] Inspired by his own personal experiences as a senior medical officer in prisoner of war camps, Archie Cochrane worked to improve how the scientific method was used in medical evidence, writing in 1971: 'the general scientific problem with which we are primarily concerned is that of testing a hypothesis that a certain treatment alters the natural history of a disease for the better'.[62] His call for the increased use of randomised controlled trials and systematic reviews led to the creation of The Cochrane Collaboration,[63] which was founded in 1993 and named after him, building on the work by Iain Chalmers and colleagues in the area of pregnancy and childbirth.[64][58]

Current use of systematic reviews in medicine

Many organisations around the world use systematic reviews, with the methodology depending on the guidelines being followed. Organisations which use systematic reviews in medicine and human health include the National Institute for Health and Care Excellence (NICE, UK), the Agency for Healthcare Research and Quality (AHRQ, USA) and the World Health Organization. Most notable among international organisations is Cochrane, a group of over 37,000 specialists in healthcare who systematically review randomised trials of the effects of prevention, treatments and rehabilitation as well as health systems interventions. When appropriate, they also include the results of other types of research. Cochrane Reviews are published in The Cochrane Database of Systematic Reviews section of the Cochrane Library. The 2015 impact factor for The Cochrane Database of Systematic Reviews was 6.103, and it was ranked 12th in the Medicine, General & Internal category.[65]

There are several types of Cochrane Review, including:[66][67][68][69]

  1. Intervention reviews assess the benefits and harms of interventions used in healthcare and health policy.
  2. Diagnostic test accuracy reviews assess how well a diagnostic test performs in diagnosing and detecting a particular disease. For conducting diagnostic test accuracy reviews, free software such as MetaDTA and CAST-HSROC in the graphical user interface is available.[70][71]
  3. Methodology reviews address issues relevant to how systematic reviews and clinical trials are conducted and reported.
  4. Qualitative reviews synthesize qualitative evidence to address questions on aspects other than effectiveness.
  5. Prognosis reviews address the probable course or future outcome(s) of people with a health problem.
  6. Overviews of Systematic Reviews (OoRs) are a new type of study to compile multiple evidence from systematic reviews into a single document that is accessible and useful to serve as a friendly front end for the Cochrane Collaboration with regard to healthcare decision-making. These are sometimes referred to as 'umbrella reviews'.
  7. Living Systematic reviews are continually updated, incorporating relevant new evidence as it becomes available.[72] They are a relatively new kind of review, with methods still being developed and evaluated. They can be high quality, semi-automated, up-to-date online summaries of research which are updated as new research becomes available.[54] The essential difference between a 'living systematic review' and a conventional systematic review is the publication format. Living systematic reviews are 'dynamic, persistent, online-only evidence summaries, which are updated rapidly and frequently'.[55]
  8. Rapid reviews are a form of knowledge synthesis that 'accelerates the process of conducting a traditional systematic review through streamlining or omitting specific methods to produce evidence for stakeholders in a resource-efficient manner'.[73]
  9. Reviews of complex health interventions in complex systems review interventions and interventions delivered in complex systems to improve evidence synthesis and guideline development at a global, national or health systems level.[74]

The Cochrane Collaboration provides a handbook for systematic reviewers of interventions which 'provides guidance to authors for the preparation of Cochrane Intervention reviews.'[36] The Cochrane Handbook also outlines the key steps for preparing a systematic review[36] and forms the basis of two sets of standards for the conduct and reporting of Cochrane Intervention Reviews (MECIR - Methodological Expectations of Cochrane Intervention Reviews).[75] It also contains guidance on how to undertake qualitative evidence synthesis, economic reviews and integrating patient-reported outcomes into reviews.

The Cochrane Library is a collection of databases that contains different types of independent evidence to inform healthcare decision-making. It contains a database of systematic review and meta-analyses which summarize and interpret the results of multi-disciplinary research. The library contains the Cochrane Database of Systematic Reviews (CDSR), which is a journal and database for systematic reviews in health care. The Cochrane Library also contains the Cochrane Central Register of Controlled Trials (CENTRAL) which is a database of reports of randomized and quasi-randomized controlled trials.[76] The Cochrane Library is also available in Spanish.[77]

The Cochrane Library is owned by Cochrane. It was originally published by Update Software and now published by the share-holder owned publisher John Wiley & Sons , Ltd. as part of Wiley Online Library. Royalties from sales of the Cochrane Library are the major source of funds for Cochrane (over £6 million in 2017). There are 3.66 billion people around the world who have access to the Library through national licences (national licences provide access to 1.5 billion individuals[78]) or free provision for populations in low- and middle-income countries eligible under the WHO's HINARI initiative.[78] Authors must pay an additional fee for their review to be truly open access.[79] Cochrane has an annual income of $10m USD.[80]

Public involvement and citizen science in systematic reviews

Cochrane has several tasks that the public or other 'stakeholders' can be involved in doing, associated with producing systematic reviews and other outputs. Tasks can be organised as 'entry level' or higher. Tasks include:

  • Joining a collaborative volunteer effort to help categorise and summarise healthcare evidence[81]
  • Data extraction and risk of bias assessment
  • Translation of reviews into other languages

A recent systematic review of how people were involved in systematic reviews aimed to document the evidence-base relating to stakeholder involvement in systematic reviews and to use this evidence to describe how stakeholders have been involved in systematic reviews.[82] Thirty percent involved patients and/or carers. The ACTIVE framework provides a way to consistently describe how people are involved in systematic review, and may be used as a way to support the decision-making of systematic review authors in planning how to involve people in future reviews.[83] Standardised Data on Initiatives (STARDIT) is another proposed way of reporting who has been involved in which tasks during research, including systematic reviews.[84][85]

While there has been some criticism of how Cochrane prioritises systematic reviews,[86] a recent project involved people in helping identify research priorities to inform future Cochrane Reviews.[87][88] In 2014, the Cochrane-Wikipedia partnership was formalised. This supports the inclusion of relevant evidence within all Wikipedia medical articles, as well as other processes to help ensure that medical information included in Wikipedia is of the highest quality and accuracy.[89]

Learning resources

Cochrane has produced many learning resources to help people understand what systematic reviews are, and how to do them. Most of the learning resources can be found at the 'Cochrane Training' webpage,[90] which also includes a link to the book Testing Treatments, which has been translated into many languages.[91] In addition, Cochrane has created a short video What are Systematic Reviews which explains in plain English how they work and what they are used for.[92] The video has been translated into multiple languages,[93] and viewed over 192,282 times (as of August 2020). In addition, an animated storyboard version was produced and all the video resources were released in multiple versions under Creative Commons for others to use and adapt.[94][95][96][97] The Critical Appraisal Skills Programme (CASP) provides free learning resources to support people to appraise research critically, including a checklist which contains 10 questions to 'help you make sense of a systematic review'.[98][99]

Social, behavioural and educational

In 1959, social scientist and social work educator Barbara Wootton published one of the first contemporary systematic reviews of literature on anti-social behavior as part of her work, Social Science and Social Pathology.[100][101]

Several organisations use systematic reviews in social, behavioural, and educational areas of evidence-based policy, including the National Institute for Health and Care Excellence (NICE, UK), Social Care Institute for Excellence (SCIE, UK), the Agency for Healthcare Research and Quality (AHRQ, USA), the World Health Organization, the International Initiative for Impact Evaluation (3ie), the Joanna Briggs Institute and the Campbell Collaboration. The quasi-standard for systematic review in the social sciences is based on the procedures proposed by the Campbell Collaboration, which is one of several groups promoting evidence-based policy in the social sciences. The Campbell Collaboration: 'helps people make well-informed decisions by preparing, maintaining and disseminating systematic reviews in education, crime and justice, social welfare and international development.'[102] The Campbell Collaboration is a sibling initiative of Cochrane, and was created in 2000 at the inaugural meeting in Philadelphia, USA, attracting 85 participants from 13 countries.[103]

Business and economics

Due to the different nature of research fields outside of the natural sciences, the aforementioned methodological steps cannot easily be applied in all areas of business research. Some attempts to transfer the procedures from medicine to business research have been made,[104] including a step-by-step approach,[105] and developing a standard procedure for conducting systematic literature reviews in business and economics. The Campbell & Cochrane Economics Methods Group (C-CEMG) works to improve the inclusion of economic evidence into Cochrane and Campbell systematic reviews of interventions, to enhance the usefulness of review findings as a component for decision-making.[106] Such economic evidence is crucial for health technology assessment processes.

International development research

Systematic reviews are increasingly prevalent in other fields, such as international development research.[107] Subsequently, several donors (including the UK Department for International Development (DFID) and AusAid) are focusing more attention and resources on testing the appropriateness of systematic reviews in assessing the impacts of development and humanitarian interventions.[107]


The Collaboration for Environmental Evidence (CEE) works to achieve a sustainable global environment and the conservation of biodiversity. The CEE has a journal titled Environmental Evidence which publishes systematic reviews, review protocols and systematic maps on impacts of human activity and the effectiveness of management interventions.[108]

Environmental health and toxicology

Systematic reviews are a relatively recent innovation in the field of environmental health and toxicology. Although mooted in the mid-2000s, the first full frameworks for conduct of systematic reviews of environmental health evidence were only published in 2014 by the US National Toxicology Program's Office of Health Assessment and Translation[109] and the Navigation Guide at the University of California San Francisco's Program on Reproductive Health and the Environment.[110] Uptake has since been rapid, with the estimated number of systematic reviews in the field doubling since 2016 and the first consensus recommendations on best practice, as a precursor to a more general standard, being published in 2020.[111]

Review tools

A 2019 publication identified 15 systematic review tools and ranked them according to the number of 'critical features' as required to perform a systematic review, including:[112]

  • DistillerSR: a proprietary, paid web application
  • Swift Active Screener: a proprietary, paid web application
  • Covidence: a proprietary, paid web application and Cochrane technology platform.
  • Rayyan: a proprietary, free of charge web application
  • Sysrev: a proprietary, freemium web application


While systematic reviews involve a highly rigorous approach to synthesizing the evidence, they still have several limitations.

Out-dated or risk of bias

While systematic reviews are regarded as the strongest form of evidence, a 2003 review of 300 studies found that not all systematic reviews were equally reliable, and that their reporting can be improved by a universally agreed upon set of standards and guidelines.[113] A further study by the same group found that of 100 systematic reviews monitored, 7% needed updating at the time of publication, another 4% within a year, and another 11% within 2 years; this figure was higher in rapidly changing fields of medicine, especially cardiovascular medicine.[114] A 2003 study suggested that extending searches beyond major databases, perhaps into grey literature, would increase the effectiveness of reviews.[115]

Some authors have highlighted problems with systematic reviews, particularly those conducted by Cochrane, noting that published reviews are often biased, out of date and excessively long.[116] Cochrane reviews have been criticized as not being sufficiently critical in the selection of trials and including too many of low quality. They proposed several solutions, including limiting studies in meta-analyses and reviews to registered clinical trials, requiring that original data be made available for statistical checking, paying greater attention to sample size estimates, and eliminating dependence on only published data.

Some of these difficulties were noted as early as 1994:

much poor research arises because researchers feel compelled for career reasons to carry out research that they are ill-equipped to perform, and nobody stops them.

Methodological limitations of meta-analysis have also been noted.[117] Another concern is that the methods used to conduct a systematic review are sometimes changed once researchers see the available trials they are going to include.[118] Some websites have described retractions of systematic reviews and published reports of studies included in published systematic reviews.[119][120][121] Eligibility criteria must be justifiable and not arbitrary (for example, the date range searched) as this may affect the perceived quality of the review.[122][123]

Limited reporting of clinical trials and data from human studies

The 'AllTrials' campaign highlights that around half of clinical trials have never reported results and works to improve reporting.[124] This lack of reporting has extremely serious implications for research, including systematic reviews, as it is only possible to synthesize data of published studies. In addition, 'positive' trials were twice as likely to be published as those with 'negative' results.[125] At present, it is legal for-profit companies to conduct clinical trials and not publish the results.[126] For example, in the past 10 years 8.7 million patients have taken part in trials that have not published results.[126] These factors mean that it is likely there is a significant publication bias, with only 'positive' or perceived favourable results being published. A recent systematic review of industry sponsorship and research outcomes concluded that 'sponsorship of drug and device studies by the manufacturing company leads to more favorable efficacy results and conclusions than sponsorship by other sources' and that the existence of an industry bias that cannot be explained by standard 'Risk of bias' assessments.[127] Systematic reviews of such a bias may amplify the effect, although it is important to note that the flaw is in the reporting of research generally, not in the systematic review method.

Poor compliance with review reporting guidelines

The rapid growth of systematic reviews in recent years has been accompanied by the attendant issue of poor compliance with guidelines, particularly in areas such as declaration of registered study protocols, funding source declaration, risk of bias data, issues resulting from data abstraction, and description of clear study objectives.[128][129][130][131][132] A host of studies have identified weaknesses in the rigour and reproducibility of search strategies in systematic reviews.[133][134][135][136][137][138] To remedy this issue, a new PRISMA guideline extension called PRISMA-S is being developed to improve the quality, reporting, and reproducibility of systematic review search strategies.[139] Furthermore, tools and checklists for peer-reviewing search strategies have been created, such as the Peer Review of Electronic Search Strategies (PRESS) guidelines.[140]

A key challenge for using systematic reviews in clinical practice and healthcare policy is assessing the quality of a given review. Consequently, a range of appraisal tools to evaluate systematic reviews have been designed. The two most popular measurement instruments and scoring tools for systematic review quality assessment are AMSTAR 2 (a measurement tool to assess the methodological quality of systematic reviews)[141][142][143] and ROBIS (Risk Of Bias In Systematic reviews); however, these are not appropriate for all systematic review types.[144]

See also


STARDIT report Q101116128.

  1. 1.0 1.1 1.2 1.3 "What is a systematic review?". Temple University Libraries. 6 June 2022. 
  2. "Cochrane Update. 'Scoping the scope' of a cochrane review". Journal of Public Health 33 (1): 147–150. March 2011. doi:10.1093/pubmed/fdr015. PMID 21345890. 
  3. "What is EBM?". Centre for Evidence Based Medicine. 2009-11-20. 
  4. "Methodological quality". Advising on Research Methods: A consultant's companion. Johannes van Kessel Publishing. 2008. ISBN 978-90-79418-02-2. 
  5. "On the use of systematic reviews to inform environmental policies". Environmental Science & Policy 42: 67–77. 2014. doi:10.1016/j.envsci.2014.05.010. 
  6. Systematic reviews: CRD's guidance for undertaking reviews in health care.. York: University of York, Centre for Reviews and Dissemination. 2008. ISBN 978-1-900640-47-3. Retrieved 17 June 2011. 
  7. Systematic reviews in the social sciences. Wiley Blackwell. 2006. ISBN 978-1-4051-2110-1. 
  8. "Qualitative synthesis and systematic review in health professions education". Medical Education 47 (3): 252–260. March 2013. doi:10.1111/medu.12092. PMID 23398011. 
  9. (in en) Cochrane Handbook for Systematic Reviews of Interventions. version 6.1. 2019-09-20. pp. section 4.6. Retrieved 2020-09-14. 
  10. "What is GRADE?" (in en). 
  11. (in en) Advising on Research Methods: A Consultant's Companion. Johannes van Kessel Publishing.. 2008. ISBN 978-90-79418-01-5. 
  12. (in en) GRADE Handbook. 2013. Retrieved 2020-08-26. 
  13. 13.0 13.1 "Cochrane Qualitative and Implementation Methods Group guidance series-paper 6: reporting guidelines for qualitative, implementation, and process evaluation evidence syntheses". Journal of Clinical Epidemiology 97: 79–85. May 2018. doi:10.1016/j.jclinepi.2017.10.022. PMID 29222060. 
  14. "Cochrane Qualitative and Implementation Methods Group guidance series-paper 5: methods for integrating qualitative and implementation evidence within intervention effectiveness reviews". Journal of Clinical Epidemiology 97: 70–78. May 2018. doi:10.1016/j.jclinepi.2017.11.029. PMID 29242095. 
  15. "EPPI-Centre Home". 
  16. 16.0 16.1 Guidance on choosing qualitative evidence synthesis methods for use in health technology assessments of complex interventions. 2016. p. 32. OCLC 944453327. 
  17. 17.0 17.1 17.2 17.3 17.4 17.5 17.6 "A typology of reviews: an analysis of 14 review types and associated methodologies". Health Information and Libraries Journal 26 (2): 91–108. June 2009. doi:10.1111/j.1471-1842.2009.00848.x. PMID 19490148. 
  18. 18.0 18.1 "Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement". 
  19. "RAMESES publication standards: meta-narrative reviews". Journal of Advanced Nursing 69 (5): 987–1004. May 2013. doi:10.1111/jan.12092. PMID 23356699. 
  20. "RAMESES publication standards: realist syntheses". Journal of Advanced Nursing 69 (5): 1005–1022. May 2013. doi:10.1111/jan.12095. PMID 23356726. 
  21. 21.0 21.1 "Scoping studies: Towards a methodological framework". International Journal of Social Research Methodology 8: 19–32. 2005. doi:10.1080/1364557032000119616. 
  22. 22.0 22.1 "PRISMA". 
  23. "What is a rapid review? Systematic Review Library Guides at CQ University". 
  24. "Home" (in en). 
  25. 25.0 25.1 25.2 "Guidance for conducting systematic scoping reviews". International Journal of Evidence-Based Healthcare 13 (3): 141–146. September 2015. doi:10.1097/XEB.0000000000000050. PMID 26134548. 
  26. 26.0 26.1 "Scoping studies: advancing the methodology". Implementation Science 5 (1): 69. September 2010. doi:10.1186/1748-5908-5-69. PMID 20854677. 
  27. 27.0 27.1 "Scoping reviews: time for clarity in definition, methods, and reporting". Journal of Clinical Epidemiology 67 (12): 1291–1294. December 2014. doi:10.1016/j.jclinepi.2014.03.013. PMID 25034198. 
  28. "Public Involvement in Global Genomics Research: A Scoping Review". Frontiers in Public Health 7: 79. 2019. doi:10.3389/fpubh.2019.00079. PMID 31024880. 
  29. 29.0 29.1 "Stakeholder involvement in systematic reviews: a protocol for a systematic review of methods, outcomes and effects". Research Involvement and Engagement 3 (1): 9. 2017-04-21. doi:10.1186/s40900-017-0060-4. PMID 29062534. 
  30. "Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach". BMC Medical Research Methodology 18 (1): 143. November 2018. doi:10.1186/s12874-018-0611-x. PMID 30453902. 
  31. "Scoping studies: towards a methodological framework". International Journal of Social Research Methodology 8 (1): 19–32. 2005-02-01. doi:10.1080/1364557032000119616. 
  32. "PRISMA Extension for Scoping Reviews (PRISMA-ScR): Checklist and Explanation". Annals of Internal Medicine 169 (7): 467–473. October 2018. doi:10.7326/M18-0850. PMID 30178033. 
  33. "PROSPERO". Centre for Reviews and Dissemination. University of York. 
  34. 34.0 34.1 34.2 34.3 34.4 34.5 34.6 "Animated Storyboard: What Are Systematic Reviews?". Cochrane Consumers and Communication. 
  35. "Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement". Systematic Reviews 4 (1): 1. January 2015. doi:10.1186/2046-4053-4-1. PMID 25554246. 
  36. 36.0 36.1 36.2 "Cochrane handbook for systematic reviews of interventions, version 5.1.0 (updated March 2011)". The Cochrane Collaboration. 
  37. "5. Handsearching" (in en). 
  38. "Literature searching for social science systematic reviews: consideration of a range of search techniques". Health Information and Libraries Journal 27 (2): 114–122. June 2010. doi:10.1111/j.1471-1842.2009.00863.x. PMID 20565552. 
  39. "Librarian co-authors correlated with higher quality reported search strategies in general internal medicine systematic reviews". Journal of Clinical Epidemiology 68 (6): 617–626. June 2015. doi:10.1016/j.jclinepi.2014.11.025. PMID 25766056. 
  40. "Use of recommended search strategies in systematic reviews and the impact of librarian involvement: a cross-sectional survey of recent authors". PLOS ONE 10 (5): e0125931. 2015-05-04. doi:10.1371/journal.pone.0125931. PMID 25938454. Bibcode2015PLoSO..1025931K. 
  41. "Impact of librarians on reporting of the literature searching component of pediatric systematic reviews". Journal of the Medical Library Association 104 (4): 267–277. October 2016. doi:10.5195/jmla.2016.139. PMID 27822147. 
  42. "Network meta-analyses could be improved by searching more sources and by involving a librarian". Journal of Clinical Epidemiology 67 (9): 1001–1007. September 2014. doi:10.1016/j.jclinepi.2014.04.003. PMID 24841794. 
  43. "Engaging medical librarians to improve the quality of review articles". JAMA 312 (10): 999–1000. September 2014. doi:10.1001/jama.2014.9263. PMID 25203078. 
  44. 44.0 44.1 "Animated Storyboard: What Are Systematic Reviews?" (in en). 
  45. "Chapter 4: Searching for and selecting studies" (in en). Cochrane Handbook for Systematic Reviews of Interventions. version 6.1. 2019-09-20. pp. section 4.6. Retrieved 2020-09-14. 
  46. "Systematic review toolbox: a catalogue of tools to support systematic reviews". Proceedings of the 19th International Conference on Evaluation and Assessment in Software Engineering. EASE '15 (Nanjing, China: Association for Computing Machinery): 1–6. 2015-04-27. doi:10.1145/2745802.2745824. ISBN 978-1-4503-3350-4. 
  47. "Developing methods for the overarching synthesis of quantitative and qualitative evidence: The interweave synthesis approach". Research Synthesis Methods 11 (4): 507–521. July 2020. doi:10.1002/jrsm.1383. PMID 31725951. 
  48. "The difference we make". 
  49. "Synthesising quantitative evidence in systematic reviews of complex health interventions". BMJ Global Health 4 (Suppl 1): e000858. 2019-01-01. doi:10.1136/bmjgh-2018-000858. PMID 30775014. 
  50. "GRADE working group". 
  51. "GRADE CERQual" (in en). 
  52. "How to disseminate your research".,-Stakeholder%20engagement:%20Work&text=Format:%20Produce%20targeted%20outputs%20that,or%20local%20levels%20as%20appropriate. 
  53. "Bursting out of our bubble: using creative techniques to communicate within the systematic review process and beyond". Systematic Reviews 11 (1): 56. April 2022. doi:10.1186/s13643-022-01935-2. PMID 35379331. 
  54. 54.0 54.1 54.2 "Systematic review automation technologies". Systematic Reviews 3 (1): 74. July 2014. doi:10.1186/2046-4053-3-74. PMID 25005128. 
  55. 55.0 55.1 "Living systematic reviews: an emerging opportunity to narrow the evidence-practice gap". PLOS Medicine 11 (2): e1001603. February 2014. doi:10.1371/journal.pmed.1001603. PMID 24558353. 
  56. "Comparison of a traditional systematic review approach with review-of-reviews and semi-automation as strategies to update the evidence". Systematic Reviews 9 (1): 243. October 2020. doi:10.1186/s13643-020-01450-2. PMID 33076975. 
  57. "Report on Certain Enteric Fever Inoculation Statistics". British Medical Journal (British Medical Journal Publishing Group) 2 (2288): 1243–1246. November 1904. doi:10.1136/bmj.2.2288.1243. PMID 20761760. 
  58. 58.0 58.1 "1.1.2 A brief history of Cochrane" (in en). 
  59. Meta-Analysis of Research on the Relationship of Class-Size and Achievement. The Class Size and Instruction Project. Washington, D.C.]: Distributed by ERIC Clearinghouse. 1978. 
  60. "History of Systematic Reviews". Evidence for Policy and Practice Information and Co-ordinating Centre (EPPI-Centre). 
  61. "Cumulative meta-analysis of therapeutic trials for myocardial infarction". The New England Journal of Medicine 327 (4): 248–254. July 1992. doi:10.1056/NEJM199207233270406. PMID 1614465. 
  62. Effectiveness and efficiency: random reflections on health services. [London]: Nuffield Provincial Hospitals Trust. 1972. ISBN 0-900574-17-8. OCLC 741462. 
  63. "Archie Cochrane and his vision for evidence-based medicine". Plastic and Reconstructive Surgery 124 (3): 982–988. September 2009. doi:10.1097/PRS.0b013e3181b03928. PMID 19730323. 
  64. Testing treatments : better research for better healthcare (Second ed.). London: Pinter & Martin. 2011. ISBN 978-1-905177-48-6. OCLC 778837501. 
  65. The Cochrane Library. 2015 impact factor. Cochrane Database of Systematic Reviews (CDSR) Retrieved 2016-07-20.
  66. Review Manager (RevMan) [Computer program]. Version 5.2. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2012.
  67. "Main page" (in en). 
  68. "Overview of systematic reviews - a new type of study. Part II". Sao Paulo Medical Journal = Revista Paulista de Medicina 133 (3): 206–217. 2015. doi:10.1590/1516-3180.2013.8150015. PMID 25388685. 
  69. "Overview of systematic reviews - a new type of study: part I: why and for whom?". Sao Paulo Medical Journal = Revista Paulista de Medicina 130 (6): 398–404. 2012. doi:10.1590/S1516-31802012000600007. PMID 23338737. 
  70. "Development of an interactive web-based tool to conduct and interrogate meta-analysis of diagnostic test accuracy studies: MetaDTA". BMC Medical Research Methodology 19 (1): 81. April 2019. doi:10.1186/s12874-019-0724-x. PMID 30999861. 
  71. "CAST-HSROC: A Web Application for Calculating the Summary Points of Diagnostic Test Accuracy From the Hierarchical Summary Receiver Operating Characteristic Model". Cureus 13 (2): e13257. February 2021. doi:10.7759/cureus.13257. PMID 33717762. 
  72. "Living systematic reviews" (in en). 
  73. "Cochrane's work on Rapid Reviews in response to COVID-19" (in en). 
  74. "Complex health interventions in complex systems: improving the process and methods for evidence-informed health decisions". BMJ Global Health 4 (Suppl 1): e000963. 2019-01-01. doi:10.1136/bmjgh-2018-000963. PMID 30775018. 
  75. "Methodological Expectations of Cochrane Intervention Reviews (MECIR)". Cochrane. 
  76. "Cochrane Controlled Register of Trials (CENTRAL)" (in en). 
  77. "Revisiones Cochrane" (in es). 
  78. 78.0 78.1 "Cochrane's Future Publishing and Open Access Arrangements". 2019-07-02. 
  79. "Open access options for the Cochrane Database of Systematic Reviews". Cochrane. 
  80. Newman, Melanie (January 2019). "Has Cochrane lost its way?". BMJ 364: k5302. doi:10.1136/bmj.k5302. PMID 30606713. 
  81. "Cochrane crowd". 
  82. "Stakeholder involvement in systematic reviews: a scoping review". Systematic Reviews 7 (1): 208. November 2018. doi:10.1186/s13643-018-0852-0. PMID 30474560. 
  83. "Development of the ACTIVE framework to describe stakeholder involvement in systematic reviews". Journal of Health Services Research & Policy 24 (4): 245–255. October 2019. doi:10.1177/1355819619841647. PMID 30997859. 
  84. [Pre-print] Standardised Data on Initiatives - STARDIT: Alpha Version. doi:10.31219/ Retrieved 2020-08-20. 
  85. "Standardised data on initiatives-STARDIT: Beta version". Research Involvement and Engagement 8 (1): 31. July 2022. doi:10.1186/s40900-022-00363-9. PMID 35854364. 
  86. Newman, Melanie (2019-01-03). "Has Cochrane lost its way?". BMJ 364: k5302. doi:10.1136/bmj.k5302. PMID 30606713. 
  87. "Selecting, refining and identifying priority Cochrane Reviews in health communication and participation in partnership with consumers and other stakeholders". Health Research Policy and Systems 17 (1): 45. April 2019. doi:10.1186/s12961-019-0444-z. PMID 31036016. 
  88. "Research priorities in health communication and participation: international survey of consumers and other stakeholders". BMJ Open 8 (5): e019481. May 2018. doi:10.1136/bmjopen-2017-019481. PMID 29739780. 
  89. "The Cochrane-Wikipedia partnership in 2016". Cochrane. 
  90. "Welcome" (in en). 
  91. "Testing Treatments". 2019-06-25. 
  92. Cochrane (2016-01-27). "What are systematic reviews?". 
  93. "Successful multi-language free online animated learning resource". Abstracts of the 24th Cochrane Colloquium; 23–27 October 2016, Seoul, South Korea. Wiley. 2016-10-23. doi:10.1002/14651858.CD201602. 
  94. "Creating a successful online animation resource: the 'what are systematic reviews?' video". 2019-06-25. 
  95. "Animated Storyboard: What Are Systematic Reviews?". Cochrane Consumers and Communication. 
  96. "Building partnerships with the public by learning about Cochrane evidence" (in en). 23rd Cochrane Colloquium 2015. 2015. doi:10.13140/RG.2.1.2182.1922. 
  97. "What are systematic reviews?" (in en). 
  98. "CASP Checklists" (in en). 
  99. "CASP Systematic Review Checklist". 2020-08-21. 
  100. An Introduction to Systematic Reviews (2nd ed.). London: Sage. 2017. p. XIII. 
  101. A critical woman : Barbara Wootton, social science and public policy in the twentieth century. London: Bloomsbury Academic. 2011. ISBN 9781849664707. 
  102. "About Us". The Campbell Collaboration. 
  103. "History of the Campbell Collaboration". 
  104. "Towards a methodology for developing evidence-informed management knowledge by means of systematic review". British Journal of Management 14 (3): 207–222. 2003. doi:10.1111/1467-8551.00375. 
  105. "A New Paradigm for Systematic Literature Reviews in Supply Chain Management". Journal of Supply Chain Management 53 (4): 67–85. 2017. doi:10.1111/jscm.12145. 
  106. "About us" (in en). 
  107. 107.0 107.1 "Making systematic reviews work for international development research". Overseas Development Institute. January 2012. 
  108. "Environmental Evidence: Reliable evidence, informed decisions, better environment". 
  109. "Systematic review and evidence integration for literature-based environmental health science assessments". Environmental Health Perspectives 122 (7): 711–718. July 2014. doi:10.1289/ehp.1307972. PMID 24755067. 
  110. "The Navigation Guide systematic review methodology: a rigorous and transparent method for translating environmental health science into better health outcomes". Environmental Health Perspectives 122 (10): 1007–1014. October 2014. doi:10.1289/ehp.1307175. PMID 24968373. 
  111. "Recommendations for the conduct of systematic reviews in toxicology and environmental health research (COSTER)". Environment International 143: 105926. October 2020. doi:10.1016/j.envint.2020.105926. PMID 32653802. 
  112. "Software tools for literature screening in systematic reviews in biomedical research". Altex 36 (3): 508–517. 2019. doi:10.14573/altex.1902131. PMID 31113000. 
  113. "Epidemiology and reporting characteristics of systematic reviews". PLOS Medicine 4 (3): e78. March 2007. doi:10.1371/journal.pmed.0040078. PMID 17388659. 
  114. "How quickly do systematic reviews go out of date? A survival analysis". Annals of Internal Medicine 147 (4): 224–233. August 2007. doi:10.7326/0003-4819-147-4-200708210-00179. PMID 17638714. 
  115. "Beyond Medline: reducing bias through extended systematic review search". International Journal of Technology Assessment in Health Care 19 (1): 168–178. 2003. doi:10.1017/S0266462303000163. PMID 12701949. 
  116. "The knowledge system underpinning healthcare is not fit for purpose and must change". BMJ 350: h2463. June 2015. doi:10.1136/bmj.h2463. PMID 26041754. 
  117. "Meta-analysis/Shmeta-analysis". American Journal of Epidemiology 140 (9): 771–778. November 1994. doi:10.1093/oxfordjournals.aje.a117324. PMID 7977286. 
  118. "Bias due to selective inclusion and reporting of outcomes and analyses in systematic reviews of randomised trials of healthcare interventions". The Cochrane Database of Systematic Reviews 2015 (10): MR000035. October 2014. doi:10.1002/14651858.MR000035.pub2. PMID 25271098. 
  119. "Retraction Of Scientific Papers For Fraud Or Bias Is Just The Tip Of The Iceberg". 
  120. "Retraction and republication for Lancet Resp Med tracheostomy paper". Retraction Watch. 2015-04-02. 
  121. "BioMed Central retracting 43 papers for fake peer review". Retraction Watch. 2015-03-26. 
  122. Flinders University Library. "Search Smart: Systematic Reviews: Methodology overview" (in en). 
  123. How to Perform a Systematic Literature Review: a guide for healthcare researchers, practitioners and students.. Springer Nature. 2020. ISBN 978-3-030-49672-2. OCLC 1182880684. 
  124. "Half of all clinical trials have never reported results". 2015-08-20. 
  125. "Dissemination and publication of research findings: an updated review of related biases". Health Technology Assessment 14 (8): iii, ix-xi, 1–193. February 2010. doi:10.3310/hta14080. PMID 20181324. 
  126. 126.0 126.1 "Nearly half of all trials run by major sponsors in past decade are unpublished". BMJ 355: i5955. November 2016. doi:10.1136/bmj.i5955. PMID 27815253. 
  127. "Industry sponsorship and research outcome". The Cochrane Database of Systematic Reviews 2017 (2): MR000033. February 2017. doi:10.1002/14651858.MR000033.pub3. PMID 28207928. 
  128. "An assessment of the compliance of systematic review articles published in craniofacial surgery with the PRISMA statement guidelines: A systematic review". Journal of Cranio-Maxillo-Facial Surgery 44 (10): 1522–1530. October 2016. doi:10.1016/j.jcms.2016.07.018. PMID 27575881. 
  129. "Compliance of Systematic Reviews in Plastic Surgery With the PRISMA Statement". JAMA Facial Plastic Surgery 18 (2): 101–105. 2016-03-01. doi:10.1001/jamafacial.2015.1726. PMID 26719993. 
  130. "Compliance of systematic reviews articles in brain arteriovenous malformation with PRISMA statement guidelines: Review of literature". Journal of Clinical Neuroscience 39: 45–48. May 2017. doi:10.1016/j.jocn.2017.02.016. PMID 28246008. 
  131. "Compliance of systematic reviews in ophthalmology with the PRISMA statement". BMC Medical Research Methodology 17 (1): 178. December 2017. doi:10.1186/s12874-017-0450-1. PMID 29281981. 
  132. "Adjudication rather than experience of data abstraction matters more in reducing errors in abstracting data in systematic reviews". Research Synthesis Methods 11 (3): 354–362. May 2020. doi:10.1002/jrsm.1396. PMID 31955502. 
  133. "Reproducibility of Search Strategies Is Poor in Systematic Reviews Published in High-Impact Pediatrics, Cardiology and Surgery Journals: A Cross-Sectional Study". PLOS ONE 11 (9): e0163309. 2016-09-26. doi:10.1371/journal.pone.0163309. PMID 27669416. Bibcode2016PLoSO..1163309K. 
  134. "Analysis of the reporting of search strategies in Cochrane systematic reviews". Journal of the Medical Library Association 97 (1): 21–29. January 2009. doi:10.3163/1536-5050.97.1.004. PMID 19158999. 
  135. "Compliance of systematic reviews in veterinary journals with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) literature search reporting guidelines". Journal of the Medical Library Association 105 (3): 233–239. July 2017. doi:10.5195/jmla.2017.246. PMID 28670210. 
  136. "Reporting quality of search methods in systematic reviews of HIV behavioral interventions (2000-2010): are the searches clearly explained, systematic and reproducible?". Research Synthesis Methods 5 (2): 116–130. June 2014. doi:10.1002/jrsm.1098. PMID 26052651. 
  137. "A review of the reporting of web searching to identify studies for Cochrane systematic reviews". Research Synthesis Methods 9 (1): 89–99. March 2018. doi:10.1002/jrsm.1275. PMID 29065246. 
  138. "Poor reporting and inadequate searches were apparent in systematic reviews of adverse effects". Journal of Clinical Epidemiology 61 (5): 440–448. May 2008. doi:10.1016/j.jclinepi.2007.06.005. PMID 18394536. 
  139. "PRISMA-S: an extension to the PRISMA statement for reporting literature searches in systematic reviews". Journal of the Medical Library Association 109 (2): 174–200. April 2021. doi:10.17605/OSF.IO/YGN9W. PMID 34285662. 
  140. "PRESS Peer Review of Electronic Search Strategies: 2015 Guideline Statement". Journal of Clinical Epidemiology 75: 40–46. July 2016. doi:10.1016/j.jclinepi.2016.01.021. PMID 27005575. 
  141. "AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both". BMJ 358: j4008. September 2017. doi:10.1136/bmj.j4008. PMID 28935701. 
  142. "Development of AMSTAR: a measurement tool to assess the methodological quality of systematic reviews". BMC Medical Research Methodology 7 (1): 10. February 2007. doi:10.1186/1471-2288-7-10. PMID 17302989. 
  143. "AMSTAR is a reliable and valid measurement tool to assess the methodological quality of systematic reviews". Journal of Clinical Epidemiology 62 (10): 1013–1020. October 2009. doi:10.1016/j.jclinepi.2008.10.009. PMID 19230606. 
  144. "ROBIS: A new tool to assess risk of bias in systematic reviews was developed". Journal of Clinical Epidemiology 69: 225–234. January 2016. doi:10.1016/j.jclinepi.2015.06.005. PMID 26092286. 

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