Systematic review

A systematic review can be designed to provide a thorough summary of current literature relevant to a research question. 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 that adhere to standards for gathering, analyzing, and reporting evidence.{{cite journal | vauthors = Bearman M, Dawson P | title = Qualitative synthesis and systematic review in health professions education | journal = Medical Education | volume = 47 | issue = 3 | pages = 252–260 | date = March 2013 | pmid = 23398011 | doi = 10.1111/medu.12092 | s2cid = 11042748 | doi-access = free }}

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.{{cite book|url=https://training.cochrane.org/handbook/current|title=Cochrane Handbook for Systematic Reviews of Interventions|date=2019-09-20|website=training.cochrane.org | veditors = Higgins JP, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA |series=version 6.1|pages=section 4.6|language=en|access-date=2020-09-14}} As evidence rating can be subjective, multiple people may be consulted to resolve any scoring differences between how evidence is rated.{{cite web| vauthors = Siemieniuk R, Guyatt G |title=What is GRADE?|url=https://bestpractice.bmj.com/info/toolkit/learn-ebm/what-is-grade/|access-date=2020-08-26|website=BMJ Best Practice|language=en}}{{cite book| vauthors = Adèr HJ |url=https://books.google.com/books?id=LCnOj4ZFyjkC|title=Advising on Research Methods: A Consultant's Companion|date=2008|publisher=Johannes van Kessel Publishing.|isbn=978-90-79418-01-5|language=en}}{{cite book |url=https://training.cochrane.org/resource/grade-handbook|title=GRADE Handbook|year=2013| veditors = Schünemann H, Brożek J, Guyatt G, Oxman A |language=en|access-date=2020-08-26}}

The EPPI-Centre, Cochrane, and the Joanna Briggs Institute have been influential in developing methods for combining both qualitative and quantitative research in systematic reviews.{{cite journal | vauthors = Flemming K, Booth A, Hannes K, Cargo M, Noyes J | title = Cochrane Qualitative and Implementation Methods Group guidance series-paper 6: reporting guidelines for qualitative, implementation, and process evaluation evidence syntheses | journal = Journal of Clinical Epidemiology | volume = 97 | pages = 79–85 | date = May 2018 | pmid = 29222060 | doi = 10.1016/j.jclinepi.2017.10.022 | url = http://eprints.whiterose.ac.uk/125099/1/1-s2.0-S0895435617313276-main.pdf }}{{cite journal | vauthors = Harden A, Thomas J, Cargo M, Harris J, Pantoja T, Flemming K, Booth A, Garside R, Hannes K, Noyes J | display-authors = 6 | title = Cochrane Qualitative and Implementation Methods Group guidance series-paper 5: methods for integrating qualitative and implementation evidence within intervention effectiveness reviews | journal = Journal of Clinical Epidemiology | volume = 97 | pages = 70–78 | date = May 2018 | pmid = 29242095 | doi = 10.1016/j.jclinepi.2017.11.029 | url = http://eprints.whiterose.ac.uk/125565/1/CQIMG%20Paper%204.pdf }}{{cite web|title=EPPI-Centre Home|url=https://eppi.ioe.ac.uk/cms/|access-date=2020-06-29|website=eppi.ioe.ac.uk}} 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 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. The latest version of this commonly used statement corresponds to PRISMA 2020 (the respective article was published in 2021).{{Cite journal |last1=Page |first1=Matthew J. |last2=McKenzie |first2=Joanne E. |last3=Bossuyt |first3=Patrick M. |last4=Boutron |first4=Isabelle |last5=Hoffmann |first5=Tammy C. |last6=Mulrow |first6=Cynthia D. |last7=Shamseer |first7=Larissa |last8=Tetzlaff |first8=Jennifer M. |last9=Akl |first9=Elie A. |last10=Brennan |first10=Sue E. |last11=Chou |first11=Roger |last12=Glanville |first12=Julie |last13=Grimshaw |first13=Jeremy M. |last14=Hróbjartsson |first14=Asbjørn |last15=Lalu |first15=Manoj M. |date=2021-03-29 |title=The PRISMA 2020 statement: an updated guideline for reporting systematic reviews |journal=BMJ (Clinical Research Ed.) |volume=372 |pages=n71 |doi=10.1136/bmj.n71 |issn=1756-1833 |pmc=8005924 |pmid=33782057}} 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. A list of PRISMA guideline extensions is hosted by the EQUATOR (Enhancing the QUAlity and Transparency Of health Research) Network.{{cite web |title=Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement|url=https://www.equator-network.org/reporting-guidelines/prisma/|access-date=2020-06-29|website=www.equator-network.org}} However, the PRISMA guidelines have been found to be limited to intervention research and the guidelines have to be changed in order to fit non-intervention research. As a result, Non-Interventional, Reproducible, and Open (NIRO) Systematic Reviews was created to counter this limitation.{{Cite journal |last1=Topor |first1=Marta |last2=Pickering |first2=Jade S. |last3=Mendes |first3=Ana Barbosa |last4=Bishop |first4=Dorothy V. M. |last5=Büttner |first5=Fionn |last6=Elsherif |first6=Mahmoud M. |last7=Evans |first7=Thomas R. |last8=Henderson |first8=Emma L. |last9=Kalandadze |first9=Tamara |last10=Nitschke |first10=Faye T. |last11=Staaks |first11=Janneke P. C. |last12=Akker |first12=Olmo R. van den |last13=Yeung |first13=Siu Kit |last14=Zaneva |first14=Mirela |last15=Lam |first15=Alison |date=2023-07-10 |title=An integrative framework for planning and conducting Non-Intervention, Reproducible, and Open Systematic Reviews (NIRO-SR). |url=https://open.lnu.se/index.php/metapsychology/article/view/2840 |journal=Meta-Psychology |language=en |volume=7 |doi=10.15626/MP.2021.2840 |issn=2003-2714|doi-access=free |hdl=11250/3106491 |hdl-access=free }}

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;{{cite journal | vauthors = Wong G, Greenhalgh T, Westhorp G, Buckingham J, Pawson R | title = RAMESES publication standards: meta-narrative reviews | journal = Journal of Advanced Nursing | volume = 69 | issue = 5 | pages = 987–1004 | date = May 2013 | pmid = 23356699 | pmc = 3558334 | doi = 10.1111/jan.12092 }}{{cite journal | vauthors = Wong G, Greenhalgh T, Westhorp G, Buckingham J, Pawson R | title = RAMESES publication standards: realist syntheses | journal = Journal of Advanced Nursing | volume = 69 | issue = 5 | pages = 1005–1022 | date = May 2013 | pmid = 23356726 | pmc = 3558331 | doi = 10.1111/jan.12095 }} and eMERGe (Improving reporting of Meta-Ethnography) for meta-ethnograph.

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.

There are over 30 types of systematic review and Table 1 below non-exhaustingly summarises some of these.{{cite journal | vauthors = Grant MJ, Booth A | title = A typology of reviews: an analysis of 14 review types and associated methodologies | journal = Health Information and Libraries Journal | volume = 26 | issue = 2 | pages = 91–108 | date = June 2009 | pmid = 19490148 | doi = 10.1111/j.1471-1842.2009.00848.x | doi-access = free }}{{cite book| vauthors = Booth A, Noyes J, Flemming K, Gerhardus A, Wahlster P, Van Der Wilt GJ, Mozygemba K, Refolo P, Sacchini D, Tummers M, Rehfuess E | display-authors = 6 |url=http://worldcat.org/oclc/944453327|title=Guidance on choosing qualitative evidence synthesis methods for use in health technology assessments of complex interventions |date=2016 |page=32 |oclc=944453327 }} There is not always consensus on the boundaries and distinctions between the approaches described below.

Scoping reviews are distinct from systematic reviews in several 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.{{cite journal| vauthors = Arksey H, O'Malley L |year=2005|title=Scoping studies: Towards a methodological framework|journal=International Journal of Social Research Methodology|volume=8|pages=19–32|doi=10.1080/1364557032000119616|hdl=11250/2477738 |s2cid=12719181|url=https://eprints.whiterose.ac.uk/1618/1/Scopingstudies.pdf}}{{cite web|title=PRISMA|url=http://www.prisma-statement.org/Extensions/ScopingReviews|access-date=2020-07-01|website=www.prisma-statement.org}} 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.{{cite journal | vauthors = Peters MD, Godfrey CM, Khalil H, McInerney P, Parker D, Soares CB | title = Guidance for conducting systematic scoping reviews | journal = International Journal of Evidence-Based Healthcare | volume = 13 | issue = 3 | pages = 141–146 | date = September 2015 | pmid = 26134548 | doi = 10.1097/XEB.0000000000000050 | s2cid = 8860037 | url = https://unisa.alma.exlibrisgroup.com/view/delivery/61USOUTHAUS_INST/12229029930001831 | doi-access = free }}{{cite journal | vauthors = Levac D, Colquhoun H, O'Brien KK | title = Scoping studies: advancing the methodology | journal = Implementation Science | volume = 5 | issue = 1 | pages = 69 | date = September 2010 | pmid = 20854677 | pmc = 2954944 | doi = 10.1186/1748-5908-5-69 | doi-access = free }} 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.{{cite journal | vauthors = Colquhoun HL, Levac D, O'Brien KK, Straus S, Tricco AC, Perrier L, Kastner M, Moher D | display-authors = 6 | title = Scoping reviews: time for clarity in definition, methods, and reporting | journal = Journal of Clinical Epidemiology | volume = 67 | issue = 12 | pages = 1291–1294 | date = December 2014 | pmid = 25034198 | doi = 10.1016/j.jclinepi.2014.03.013 | hdl-access = free | hdl = 1807/73365 | s2cid = 205843946 }} 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,{{cite journal | vauthors = Nunn JS, Tiller J, Fransquet P, Lacaze P | title = Public Involvement in Global Genomics Research: A Scoping Review | journal = Frontiers in Public Health | volume = 7 | pages = 79 | date = 2019 | pmid = 31024880 | pmc = 6467093 | doi = 10.3389/fpubh.2019.00079 | doi-access = free }} for example, exploring how the public are involved in all stages systematic reviews.{{cite journal | vauthors = Pollock A, Campbell P, Struthers C, Synnot A, Nunn J, Hill S, Goodare H, Watts C, Morley R | display-authors = 6 | title = Stakeholder involvement in systematic reviews: a protocol for a systematic review of methods, outcomes and effects | journal = Research Involvement and Engagement | volume = 3 | issue = 1 | pages = 9 | date = 2017-04-21 | pmid = 29062534 | pmc = 5611627 | doi = 10.1186/s40900-017-0060-4 | doi-access = free }}

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.{{cite journal | vauthors = Munn Z, Peters MD, Stern C, Tufanaru C, McArthur A, Aromataris E | title = Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach | journal = BMC Medical Research Methodology | volume = 18 | issue = 1 | pages = 143 | date = November 2018 | pmid = 30453902 | pmc = 6245623 | doi = 10.1186/s12874-018-0611-x | doi-access = free }} There have been several attempts to improve the standardisation of the method,{{cite journal| vauthors = Arksey H, O'Malley L |date=2005-02-01|title=Scoping studies: towards a methodological framework|journal=International Journal of Social Research Methodology|volume=8|issue=1|pages=19–32|doi=10.1080/1364557032000119616 |hdl=11250/2477738 |s2cid=12719181|url=https://eprints.whiterose.ac.uk/1618/1/Scopingstudies.pdf}} for example via a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline extension for scoping reviews (PRISMA-ScR).{{cite journal | vauthors = Tricco AC, Lillie E, Zarin W, O'Brien KK, Colquhoun H, Levac D, Moher D, Peters MD, Horsley T, Weeks L, Hempel S, Akl EA, Chang C, McGowan J, Stewart L, Hartling L, Aldcroft A, Wilson MG, Garritty C, Lewin S, Godfrey CM, Macdonald MT, Langlois EV, Soares-Weiser K, Moriarty J, Clifford T, Tunçalp Ö, Straus SE | display-authors = 6 | title = PRISMA Extension for Scoping Reviews (PRISMA-ScR): Checklist and Explanation | journal = Annals of Internal Medicine | volume = 169 | issue = 7 | pages = 467–473 | date = October 2018 | pmid = 30178033 | doi = 10.7326/M18-0850 | s2cid = 52150954 | url = https://eprints.whiterose.ac.uk/136633/1/PRISMA_ScR_Manuscript_July6th_clean_1_.pdf }} PROSPERO (the International Prospective Register of Systematic Reviews) does not permit the submission of protocols of scoping reviews,{{cite web|title=PROSPERO|url=https://www.crd.york.ac.uk/prospero/#aboutregpage|access-date=2019-02-24|work=Centre for Reviews and Dissemination|publisher=University of York}} although some journals will publish protocols for scoping reviews.

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

Some reported that the 'best practices' involve 'defining an answerable question' and 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.{{cite web|title=Animated Storyboard: What Are Systematic Reviews?|url=https://cccrg.cochrane.org/animated-storyboard-what-are-systematic-reviews|access-date=1 June 2016|website=cccrg.cochrane.org|publisher=Cochrane Consumers and Communication}}{{cite journal | vauthors = Moher D, Shamseer L, Clarke M, Ghersi D, Liberati A, Petticrew M, Shekelle P, Stewart LA | display-authors = 6 | title = Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement | journal = Systematic Reviews | volume = 4 | issue = 1 | pages = 1 | date = January 2015 | pmid = 25554246 | pmc = 4320440 | doi = 10.1186/2046-4053-4-1 | doi-access = free }} Clinical reviews of quantitative data are often structured using the mnemonic 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'.

Relevant criteria can include selecting research that is of good quality and answers the defined question. 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 predetermined 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, or the standards of Cochrane.{{cite web|title=Cochrane handbook for systematic reviews of interventions, version 5.1.0 (updated March 2011)|url=http://handbook.cochrane.org|access-date=2 June 2016|publisher=The Cochrane Collaboration|veditors=Higgins JP, Green S}}

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'),{{cite web|title=5. Handsearching|url=https://training.cochrane.org/resource/tsc-induction-mentoring-training-guide/5-handsearching|access-date=2020-09-14|website=training.cochrane.org|language=en}} and directly contacting experts in the field.{{cite journal | vauthors = Papaioannou D, Sutton A, Carroll C, Booth A, Wong R | title = Literature searching for social science systematic reviews: consideration of a range of search techniques | journal = Health Information and Libraries Journal | volume = 27 | issue = 2 | pages = 114–122 | date = June 2010 | pmid = 20565552 | doi = 10.1111/j.1471-1842.2009.00863.x | doi-access = free }}

To be systematic, searchers must use a combination of search skills and tools such as database subject headings, keyword searching, Boolean operators, and proximity searching while attempting to balance sensitivity (systematicity) and precision (accuracy). Inviting and involving an experienced information professional or librarian can improve the quality of systematic review search strategies and reporting.{{cite journal | vauthors = Rethlefsen ML, Farrell AM, Osterhaus Trzasko LC, Brigham TJ | title = Librarian co-authors correlated with higher quality reported search strategies in general internal medicine systematic reviews | journal = Journal of Clinical Epidemiology | volume = 68 | issue = 6 | pages = 617–626 | date = June 2015 | pmid = 25766056 | doi = 10.1016/j.jclinepi.2014.11.025 }}{{cite journal | vauthors = Koffel JB | title = Use of recommended search strategies in systematic reviews and the impact of librarian involvement: a cross-sectional survey of recent authors | journal = PLOS ONE | volume = 10 | issue = 5 | pages = e0125931 | date = 2015-05-04 | pmid = 25938454 | pmc = 4418838 | doi = 10.1371/journal.pone.0125931 | doi-access = free | bibcode = 2015PLoSO..1025931K }}{{cite journal | vauthors = Meert D, Torabi N, Costella J | title = Impact of librarians on reporting of the literature searching component of pediatric systematic reviews | journal = Journal of the Medical Library Association | volume = 104 | issue = 4 | pages = 267–277 | date = October 2016 | pmid = 27822147 | pmc = 5079487 | doi = 10.5195/jmla.2016.139 }}{{cite journal | vauthors = Li L, Tian J, Tian H, Moher D, Liang F, Jiang T, Yao L, Yang K | display-authors = 6 | title = Network meta-analyses could be improved by searching more sources and by involving a librarian | journal = Journal of Clinical Epidemiology | volume = 67 | issue = 9 | pages = 1001–1007 | date = September 2014 | pmid = 24841794 | doi = 10.1016/j.jclinepi.2014.04.003 }}{{cite journal | vauthors = Rethlefsen ML, Murad MH, Livingston EH | title = Engaging medical librarians to improve the quality of review articles | journal = JAMA | volume = 312 | issue = 10 | pages = 999–1000 | date = September 2014 | pmid = 25203078 | doi = 10.1001/jama.2014.9263 }}

File:Extraction machine.gif

Relevant data are 'extracted' from the data sources according to the review method. 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). Relevant data are being extracted and 'combined' in an intervention effect review, where a meta-analysis is possible.

This stage involves assessing the eligibility of data for inclusion in the review by judging it against criteria identified at the first stage. 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 programmes can be used to support the selection process, including text mining tools and machine learning, which can automate aspects of the process.{{cite book | url=https://training.cochrane.org/handbook/current|title=Cochrane Handbook for Systematic Reviews of Interventions|date=2019-09-20|website=training.cochrane.org| veditors = Higgins JP, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA |series=version 6.1|pages=section 4.6|no-pp=y|language=en|chapter=Chapter 4: Searching for and selecting studies|access-date=2020-09-14 |chapter-url=https://training.cochrane.org/handbook/current/chapter-04#section-4-6}} The 'Systematic Review Toolbox' is a community-driven, web-based catalog of tools, to help reviewers chose appropriate tools for reviews.{{cite book| vauthors = Marshall C, Brereton P |title=Proceedings of the 19th International Conference on Evaluation and Assessment in Software Engineering |chapter=Systematic review toolbox |date=2015-04-27|series=EASE '15|location=Nanjing, China|publisher=Association for Computing Machinery|pages=1–6|doi=10.1145/2745802.2745824|isbn=978-1-4503-3350-4|s2cid=6679820}}

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.{{cite journal | vauthors = Thompson Coon J, Gwernan-Jones R, Garside R, Nunns M, Shaw L, Melendez-Torres GJ, Moore D | title = Developing methods for the overarching synthesis of quantitative and qualitative evidence: The interweave synthesis approach | journal = Research Synthesis Methods | volume = 11 | issue = 4 | pages = 507–521 | date = July 2020 | pmid = 31725951 | pmc = 7383598 | doi = 10.1002/jrsm.1383 }} The combination of data from a meta-analysis can sometimes be visualised. One method uses a forest plot (also called a blobbogram). In an intervention effect review, the diamond in the 'forest plot' represents the combined results of all the data included. An example of a 'forest plot' is the Cochrane Collaboration logo. 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.{{cite web|title=The difference we make|url=https://www.cochrane.org/about-us/difference-we-make|access-date=2019-03-08|website=www.cochrane.org}}

Recent visualisation innovations include the albatross plot, which plots p-values against sample sizes, with approximate effect-size contours superimposed to facilitate analysis.{{cite journal | vauthors = Higgins JP, López-López JA, Becker BJ, Davies SR, Dawson S, Grimshaw JM, McGuinness LA, Moore TH, Rehfuess EA, Thomas J, Caldwell DM | display-authors = 6 | title = Synthesising quantitative evidence in systematic reviews of complex health interventions | journal = BMJ Global Health | volume = 4 | issue = Suppl 1 | pages = e000858 | date = 2019-01-01 | pmid = 30775014 | pmc = 6350707 | doi = 10.1136/bmjgh-2018-000858 }} 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.

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".{{Cite web |title=How to disseminate your research |url=https://www.nihr.ac.uk/documents/how-to-disseminate-your-research/19951#:~:text=Principles%20of%20good%20dissemination,-Stakeholder%20engagement:%20Work&text=Format:%20Produce%20targeted%20outputs%20that,or%20local%20levels%20as%20appropriate |access-date=2022-05-20 |website=www.nihr.ac.uk}}

Some 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.{{cite journal | vauthors = Coon JT, Orr N, Shaw L, Hunt H, Garside R, Nunns M, Gröppel-Wegener A, Whear B | display-authors = 6 | title = Bursting out of our bubble: using creative techniques to communicate within the systematic review process and beyond | journal = Systematic Reviews | volume = 11 | issue = 1 | pages = 56 | date = April 2022 | pmid = 35379331 | pmc = 8977563 | doi = 10.1186/s13643-022-01935-2 | doi-access = free }}

Living systematic reviews are a newer kind of semi-automated, up-to-date online summaries of research that are updated as new research becomes available.{{cite journal | vauthors = Tsafnat G, Glasziou P, Choong MK, Dunn A, Galgani F, Coiera E | title = Systematic review automation technologies | journal = Systematic Reviews | volume = 3 | issue = 1 | pages = 74 | date = July 2014 | pmid = 25005128 | pmc = 4100748 | doi = 10.1186/2046-4053-3-74 | doi-access = free }} The 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".{{cite journal | vauthors = Elliott JH, Turner T, Clavisi O, Thomas J, Higgins JP, Mavergames C, Gruen RL | title = Living systematic reviews: an emerging opportunity to narrow the evidence-practice gap | journal = PLOS Medicine | volume = 11 | issue = 2 | pages = e1001603 | date = February 2014 | pmid = 24558353 | pmc = 3928029 | doi = 10.1371/journal.pmed.1001603 | doi-access = free }}

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.{{cite journal | vauthors = Reddy SM, Patel S, Weyrich M, Fenton J, Viswanathan M | title = Comparison of a traditional systematic review approach with review-of-reviews and semi-automation as strategies to update the evidence | journal = Systematic Reviews | volume = 9 | issue = 1 | pages = 243 | date = October 2020 | pmid = 33076975 | pmc = 7574591 | doi = 10.1186/s13643-020-01450-2 | doi-access = free }}

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, US), 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. They sometimes 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.The Cochrane Library. [http://www.cochrane.org/news/2015-impact-factor-released-cochrane-database-systematic-reviews 2015 impact factor. Cochrane Database of Systematic Reviews (CDSR)] {{Webarchive|url=https://web.archive.org/web/20160702164207/http://www.cochrane.org/news/2015-impact-factor-released-cochrane-database-systematic-reviews |date=2 July 2016 }} Retrieved 2016-07-20.

There are several types of systematic reviews, including:[http://tech.cochrane.org/revman Review Manager (RevMan) [Computer program]]. Version 5.2. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2012.{{cite web |title=Main page|url=https://www.cochranelibrary.com/|website=Cochrane Library|language=en}}{{cite journal | vauthors = Silva V, Grande AJ, Carvalho AP, Martimbianco AL, Riera R | title = Overview of systematic reviews - a new type of study. Part II | journal = Sao Paulo Medical Journal = Revista Paulista de Medicina | volume = 133 | issue = 3 | pages = 206–217 | year = 2015 | pmid = 25388685 | doi = 10.1590/1516-3180.2013.8150015 | doi-access = free | pmc = 10876375 }}{{cite journal | vauthors = Silva V, Grande AJ, Martimbianco AL, Riera R, Carvalho AP | title = Overview of systematic reviews - a new type of study: part I: why and for whom? | journal = Sao Paulo Medical Journal = Revista Paulista de Medicina | volume = 130 | issue = 6 | pages = 398–404 | year = 2012 | pmid = 23338737 | doi = 10.1590/S1516-31802012000600007 | pmc = 10522321 | doi-access = free }}

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.{{cite journal | vauthors = Freeman SC, Kerby CR, Patel A, Cooper NJ, Quinn T, Sutton AJ | title = Development of an interactive web-based tool to conduct and interrogate meta-analysis of diagnostic test accuracy studies: MetaDTA | journal = BMC Medical Research Methodology | volume = 19 | issue = 1 | pages = 81 | date = April 2019 | pmid = 30999861 | pmc = 6471890 | doi = 10.1186/s12874-019-0724-x | doi-access = free }}{{cite journal | vauthors = Banno M, Tsujimoto Y, Luo Y, Miyakoshi C, Kataoka Y | title = CAST-HSROC: A Web Application for Calculating the Summary Points of Diagnostic Test Accuracy From the Hierarchical Summary Receiver Operating Characteristic Model | journal = Cureus | volume = 13 | issue = 2 | pages = e13257 | date = February 2021 | pmid = 33717762 | pmc = 7953362 | doi = 10.7759/cureus.13257 | doi-access = free }}
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) compile multiple pieces of evidence from systematic reviews into a single accessible document, sometimes referred to as umbrella reviews.
7. Living systematic reviews are continually updated, incorporating relevant new evidence as it becomes available.{{cite web|title=Living systematic reviews|url=https://community.cochrane.org/review-production/production-resources/living-systematic-reviews|access-date=2020-07-01|website=community.cochrane.org|language=en}}
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".{{cite news|title=Cochrane's work on Rapid Reviews in response to COVID-19|url=https://www.cochrane.org/cochranes-work-rapid-reviews-response-covid-19|access-date=2020-07-01|website=www.cochrane.org|language=en}}
9. Reviews of complex health interventions in complex systems are to improve evidence synthesis and guideline development.{{cite journal | vauthors = Norris SL, Rehfuess EA, Smith H, Tunçalp Ö, Grimshaw JM, Ford NP, Portela A | title = Complex health interventions in complex systems: improving the process and methods for evidence-informed health decisions | journal = BMJ Global Health | volume = 4 | issue = Suppl 1 | pages = e000963 | date = 2019-01-01 | pmid = 30775018 | pmc = 6350736 | doi = 10.1136/bmjgh-2018-000963 }}

{{Further information|Patient and public involvement}}

There are various ways patients and the public can be involved in producing systematic reviews and other outputs. Tasks for public members can be organised as 'entry level' or higher. Tasks include:

• Joining a collaborative volunteer effort to help categorise and summarise healthcare evidence{{cite web|title=Cochrane crowd|url=http://crowd.cochrane.org/index.html|access-date=2019-02-14|website=crowd.cochrane.org}}
• Data extraction and risk of bias assessment
• Translation of reviews into other languages

A 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.{{cite journal | vauthors = Pollock A, Campbell P, Struthers C, Synnot A, Nunn J, Hill S, Goodare H, Morris J, Watts C, Morley R | display-authors = 6 | title = Stakeholder involvement in systematic reviews: a scoping review | journal = Systematic Reviews | volume = 7 | issue = 1 | pages = 208 | date = November 2018 | pmid = 30474560 | pmc = 6260873 | doi = 10.1186/s13643-018-0852-0 | doi-access = free }} Thirty percent involved patients and/or carers. The ACTIVE framework provides a way to describe how people are involved in systematic review and may be used as a way to support systematic review authors in planning people's involvement.{{cite journal | vauthors = Pollock A, Campbell P, Struthers C, Synnot A, Nunn J, Hill S, Goodare H, Morris J, Watts C, Morley R | display-authors = 6 | title = Development of the ACTIVE framework to describe stakeholder involvement in systematic reviews | journal = Journal of Health Services Research & Policy | volume = 24 | issue = 4 | pages = 245–255 | date = October 2019 | pmid = 30997859 | doi = 10.1177/1355819619841647 | s2cid = 121348214 | url = https://discovery.dundee.ac.uk/ws/files/31267968/JHSRP_ACTIVE_framework_final_author_accepted_version.pdf }} Standardised Data on Initiatives (STARDIT) is another proposed way of reporting who has been involved in which tasks during research, including systematic reviews.[Pre-print] {{cite journal | vauthors = Nunn J, Shafee T, Chang S, Stephens R, Elliott J, Oliver S, John D, Smith M, Orr N |title=Standardised Data on Initiatives - STARDIT: Alpha Version|url=https://osf.io/5q47h/|access-date=2020-08-20|website=osf.io|doi=10.31219/osf.io/5q47h |s2cid=242815262}}{{cite journal | vauthors = Nunn JS, Shafee T, Chang S, Stephens R, Elliott J, Oliver S, John D, Smith M, Orr N, Preston J, Borthwick J, van Vlijmen T, Ansell J, Houyez F, de Sousa MS, Plotz RD, Oliver JL, Golumbic Y, Macniven R, Wines S, Borda A, da Silva Hyldmo H, Hsing PY, Denis L, Thompson C | display-authors = 6 | title = Standardised data on initiatives-STARDIT: Beta version | journal = Research Involvement and Engagement | volume = 8 | issue = 1 | pages = 31 | date = July 2022 | pmid = 35854364 | pmc = 9294764 | doi = 10.1186/s40900-022-00363-9 | doi-access = free }}

There has been some criticism of how Cochrane prioritises systematic reviews.{{cite journal | title = Has Cochrane lost its way? | journal = BMJ | volume = 364 | pages = k5302 | date = 2019-01-03 | pmid = 30606713 | doi = 10.1136/bmj.k5302 | s2cid = 58623482 | last1 = Newman | first1 = Melanie }} Cochrane has a project that involved people in helping identify research priorities to inform Cochrane Reviews.{{cite journal | vauthors = Synnot AJ, Tong A, Bragge P, Lowe D, Nunn JS, O'Sullivan M, Horvat L, Kay D, Ghersi D, McDonald S, Poole N, Bourke N, Lannin NA, Vadasz D, Oliver S, Carey K, Hill SJ | display-authors = 6 | title = Selecting, refining and identifying priority Cochrane Reviews in health communication and participation in partnership with consumers and other stakeholders | journal = Health Research Policy and Systems | volume = 17 | issue = 1 | pages = 45 | date = April 2019 | pmid = 31036016 | pmc = 6489310 | doi = 10.1186/s12961-019-0444-z | doi-access = free }}{{cite journal | vauthors = Synnot A, Bragge P, Lowe D, Nunn JS, O'Sullivan M, Horvat L, Tong A, Kay D, Ghersi D, McDonald S, Poole N, Bourke N, Lannin N, Vadasz D, Oliver S, Carey K, Hill SJ | display-authors = 6 | title = Research priorities in health communication and participation: international survey of consumers and other stakeholders | journal = BMJ Open | volume = 8 | issue = 5 | pages = e019481 | date = May 2018 | pmid = 29739780 | pmc = 5942413 | doi = 10.1136/bmjopen-2017-019481 }} In 2014, the Cochrane–Wikipedia partnership was formalised.{{cite web|title=The Cochrane-Wikipedia partnership in 2016|url=https://www.cochrane.org/news/cochrane-wikipedia-partnership-2016-0|access-date=2019-02-24|work=Cochrane}}

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 published in 2014 by the US National Toxicology Program's Office of Health Assessment and Translation{{cite journal |vauthors=Rooney AA, Boyles AL, Wolfe MS, Bucher JR, Thayer KA |date=July 2014 |title=Systematic review and evidence integration for literature-based environmental health science assessments |journal=Environmental Health Perspectives |volume=122 |issue=7 |pages=711–718 |doi=10.1289/ehp.1307972 |pmc=4080517 |pmid=24755067|bibcode=2014EnvHP.122..711R }} and the Navigation Guide at the University of California San Francisco's Program on Reproductive Health and the Environment.{{cite journal |vauthors=Woodruff TJ, Sutton P |date=October 2014 |title=The Navigation Guide systematic review methodology: a rigorous and transparent method for translating environmental health science into better health outcomes |journal=Environmental Health Perspectives |volume=122 |issue=10 |pages=1007–1014 |doi=10.1289/ehp.1307175 |pmc=4181919 |pmid=24968373|bibcode=2014EnvHP.122.1007W }} 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.{{cite journal |display-authors=6 |vauthors=Whaley P, Aiassa E, Beausoleil C, Beronius A, Bilotta G, Boobis A, de Vries R, Hanberg A, Hoffmann S, Hunt N, Kwiatkowski CF, Lam J, Lipworth S, Martin O, Randall N, Rhomberg L, Rooney AA, Schünemann HJ, Wikoff D, Wolffe T, Halsall C |date=October 2020 |title=Recommendations for the conduct of systematic reviews in toxicology and environmental health research (COSTER) |journal=Environment International |volume=143 |pages=105926 |bibcode=2020EnInt.14305926W |doi=10.1016/j.envint.2020.105926 |pmid=32653802 |s2cid=220502683 |doi-access=free |hdl-access=free |hdl=2066/229303}}

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.{{cite book | vauthors = Gough D, Oliver S, Thomas J |title=An Introduction to Systematic Reviews |date=2017 |publisher=Sage |location=London |page=XIII |edition=2nd}}{{cite book | vauthors = Oakley A |title=A critical woman : Barbara Wootton, social science and public policy in the twentieth century |date=2011 |publisher=Bloomsbury Academic |location=London |isbn=9781849664707}}

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, US), 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.{{cite web|title=History of the Campbell Collaboration|url=https://www.campbellcollaboration.org/about-campbell/history.html|access-date=2021-04-15|website=Campbell Collaboration}}

Some attempts to transfer the procedures from medicine to business research have been made,{{cite journal|vauthors=Tranfield D, Denyer D, Smart P|year=2003|title=Towards a methodology for developing evidence-informed management knowledge by means of systematic review|journal=British Journal of Management|volume=14|issue=3|pages=207–222|citeseerx=10.1.1.622.895|doi=10.1111/1467-8551.00375}} including a step-by-step approach,{{cite journal|vauthors=Durach CF, Kembro J, Wieland A|year=2017|title=A New Paradigm for Systematic Literature Reviews in Supply Chain Management|journal=Journal of Supply Chain Management|volume=53|issue=4|pages=67–85|doi=10.1111/jscm.12145}}{{Cite journal |last1=Linnenluecke |first1=Martina K |last2=Marrone |first2=Mauricio |last3=Singh |first3=Abhay K |date=May 2020 |title=Conducting systematic literature reviews and bibliometric analyses |url=http://journals.sagepub.com/doi/10.1177/0312896219877678 |journal=Australian Journal of Management |language=en |volume=45 |issue=2 |pages=175–194 |doi=10.1177/0312896219877678 |issn=0312-8962}} and developing a standard procedure for conducting systematic literature reviews in business and economics.

Systematic reviews are increasingly prevalent in other fields, such as international development research.{{cite web| vauthors = Hagen-Zanker J, Duvendack M, Mallett R, Slater R, Carpenter S, Tromme M |date=January 2012|title=Making systematic reviews work for international development research|url=http://www.odi.org.uk/resources/details.asp?id=6260&title=systematic-review-slrc-international-development-research-methods|publisher=Overseas Development Institute}} Subsequently, several donors (including the UK Department for International Development (DFID) and AusAid) are focusing more on testing the appropriateness of systematic reviews in assessing the impacts of development and humanitarian interventions.

The Collaboration for Environmental Evidence (CEE) has a journal titled Environmental Evidence, which publishes systematic reviews, review protocols, and systematic maps on the impacts of human activity and the effectiveness of management interventions.{{cite web|title=Environmental Evidence: Reliable evidence, informed decisions, better environment|url=https://www.environmentalevidence.org/|access-date=2020-07-01|website=www.environmentalevidence.org}}

A 2022 publication identified 24 systematic review tools and ranked them by inclusion of 30 features deemed most important when performing a systematic review in accordance with best practices. The top six software tools (with at least 21/30 key features) are all proprietary paid platforms, typically web-based, and include:{{cite journal | vauthors = Cowie K, Rahmatullah A, Hardy N, Holub K, Kallmes K | title = Web-Based Software Tools for Systematic Literature Review in Medicine: Systematic Search and Feature Analysis | journal = JMIR | volume = 10 | issue = 5 | pages = e33219 | date = 2022 | pmid = 35499859 | doi = 10.2196/33219 | pmc = 9112080 | doi-access = free }}

• Giotto Compliance
• DistillerSR
• Nested Knowledge
• EPPI-Reviewer Web
• LitStream
• JBI SUMARI

The Cochrane Collaboration provides a handbook for systematic reviewers of interventions which "provides guidance to authors for the preparation of Cochrane Intervention reviews." The Cochrane Handbook also outlines steps for preparing a systematic review 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).{{cite web |title=Methodological Expectations of Cochrane Intervention Reviews (MECIR) |url=http://www.editorial-unit.cochrane.org/mecir |access-date=6 October 2014 |publisher=Cochrane}} It also contains guidance on integrating patient-reported outcomes into reviews.

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.{{cite journal | vauthors = Moher D, Tetzlaff J, Tricco AC, Sampson M, Altman DG | title = Epidemiology and reporting characteristics of systematic reviews | journal = PLOS Medicine | volume = 4 | issue = 3 | pages = e78 | date = March 2007 | pmid = 17388659 | pmc = 1831728 | doi = 10.1371/journal.pmed.0040078 | doi-access = free }} 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.{{cite journal | vauthors = Shojania KG, Sampson M, Ansari MT, Ji J, Doucette S, Moher D | title = How quickly do systematic reviews go out of date? A survival analysis | journal = Annals of Internal Medicine | volume = 147 | issue = 4 | pages = 224–233 | date = August 2007 | pmid = 17638714 | doi = 10.7326/0003-4819-147-4-200708210-00179 | s2cid = 3988259 }} A 2003 study suggested that extending searches beyond major databases, perhaps into grey literature, would increase the effectiveness of reviews.{{cite journal | vauthors = Savoie I, Helmer D, Green CJ, Kazanjian A | title = Beyond Medline: reducing bias through extended systematic review search | journal = International Journal of Technology Assessment in Health Care | volume = 19 | issue = 1 | pages = 168–178 | year = 2003 | pmid = 12701949 | doi = 10.1017/S0266462303000163 | s2cid = 42494895 }}

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.{{cite journal | vauthors = Roberts I, Ker K, Edwards P, Beecher D, Manno D, Sydenham E | title = The knowledge system underpinning healthcare is not fit for purpose and must change | journal = BMJ | volume = 350 | pages = h2463 | date = June 2015 | pmid = 26041754 | doi = 10.1136/bmj.h2463 | s2cid = 33523612 | url = https://researchonline.lshtm.ac.uk/id/eprint/2210686/1/bmj.h2463.full.pdf }} 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:{{blockquote|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.|author= Altman DG, 1994{{cite journal | vauthors = Altman DG | title = The scandal of poor medical research | journal = BMJ | volume = 308 | issue = 6924 | pages = 283–284 | date = January 1994 | pmid = 8124111 | pmc = 2539276 | doi = 10.1136/bmj.308.6924.283 }}|source=}}

Methodological limitations of meta-analysis have also been noted.{{cite journal | vauthors = Shapiro S | title = Meta-analysis/Shmeta-analysis | journal = American Journal of Epidemiology | volume = 140 | issue = 9 | pages = 771–778 | date = November 1994 | pmid = 7977286 | doi = 10.1093/oxfordjournals.aje.a117324 }} 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.{{cite journal | vauthors = Page MJ, McKenzie JE, Kirkham J, Dwan K, Kramer S, Green S, Forbes A | title = Bias due to selective inclusion and reporting of outcomes and analyses in systematic reviews of randomised trials of healthcare interventions | journal = The Cochrane Database of Systematic Reviews | volume = 2015 | issue = 10 | pages = MR000035 | date = October 2014 | pmid = 25271098 | pmc = 8191366 | doi = 10.1002/14651858.MR000035.pub2 }} Some websites have described retractions of systematic reviews and published reports of studies included in published systematic reviews.{{cite web| vauthors = Roberts I |title=Retraction Of Scientific Papers For Fraud Or Bias Is Just The Tip Of The Iceberg|url=http://www.iflscience.com/editors-blog/retraction-scientific-papers-fraud-or-bias-just-tip-iceberg|access-date=29 June 2015|website=IFL Science!|date=12 June 2015 }}{{cite web| vauthors = Ferguson C |date=2015-04-02|title=Retraction and republication for Lancet Resp Med tracheostomy paper|url=http://retractionwatch.com/2015/04/02/retraction-and-republication-for-lancet-resp-med-tracheostomy-paper/|access-date=29 June 2015|work=Retraction Watch}}{{cite web| vauthors = Ferguson C |date=2015-03-26|title=BioMed Central retracting 43 papers for fake peer review|url=http://retractionwatch.com/2015/03/26/biomed-central-retracting-43-papers-for-fake-peer-review/|work=Retraction Watch}} Eligibility criteria that is arbitrary may affect the perceived quality of the review.{{cite web| author = Flinders University Library |title=Search Smart: Systematic Reviews: Methodology overview|url=https://flinders.libguides.com/c.php?g=220637&p=1460288|access-date=2020-09-16 |website=flinders.libguides.com |language=en }}{{cite book| vauthors = Pursell E, McCrae N |url= https://www.worldcat.org/oclc/1182880684 |title=How to Perform a Systematic Literature Review: a guide for healthcare researchers, practitioners and students.|date=2020|publisher=Springer Nature|isbn=978-3-030-49672-2|oclc=1182880684}}

The AllTrials campaign report that around half of clinical trials have never reported results and works to improve reporting.{{cite web | date=2015-08-20|title=Half of all clinical trials have never reported results|url=http://www.alltrials.net/news/half-of-all-trials-unreported/|access-date=2019-03-08|website=AllTrials}} 'Positive' trials were twice as likely to be published as those with 'negative' results.{{cite journal | vauthors = Song F, Parekh S, Hooper L, Loke YK, Ryder J, Sutton AJ, Hing C, Kwok CS, Pang C, Harvey I | display-authors = 6 | title = Dissemination and publication of research findings: an updated review of related biases | journal = Health Technology Assessment | volume = 14 | issue = 8 | pages = iii, ix-xi, 1–193 | date = February 2010 | pmid = 20181324 | doi = 10.3310/hta14080 | doi-access = free }}

As of 2016, it is legal for-profit companies to conduct clinical trials and not publish the results.{{cite journal | vauthors = Iacobucci G | title = Nearly half of all trials run by major sponsors in past decade are unpublished | journal = BMJ | volume = 355 | pages = i5955 | date = November 2016 | pmid = 27815253 | doi = 10.1136/bmj.i5955 | s2cid = 43604202 }} For example, in the past 10 years, 8.7 million patients have taken part in trials that have not published results. 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.{{cite journal | vauthors = Lundh A, Lexchin J, Mintzes B, Schroll JB, Bero L | title = Industry sponsorship and research outcome | journal = The Cochrane Database of Systematic Reviews | volume = 2017 | issue = 2 | pages = MR000033 | date = February 2017 | pmid = 28207928 | pmc = 8132492 | doi = 10.1002/14651858.MR000033.pub3 | collaboration = Cochrane Methodology Review Group }}

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.{{cite journal | vauthors = Pidgeon TE, Wellstead G, Sagoo H, Jafree DJ, Fowler AJ, Agha RA | title = An assessment of the compliance of systematic review articles published in craniofacial surgery with the PRISMA statement guidelines: A systematic review | journal = Journal of Cranio-Maxillo-Facial Surgery | volume = 44 | issue = 10 | pages = 1522–1530 | date = October 2016 | pmid = 27575881 | doi = 10.1016/j.jcms.2016.07.018 }}{{cite journal | vauthors = Lee SY, Sagoo H, Whitehurst K, Wellstead G, Fowler AJ, Agha RA, Orgill D | title = Compliance of Systematic Reviews in Plastic Surgery With the PRISMA Statement | journal = JAMA Facial Plastic Surgery | volume = 18 | issue = 2 | pages = 101–105 | date = 2016-03-01 | pmid = 26719993 | doi = 10.1001/jamafacial.2015.1726 | doi-access = free }}{{cite journal | vauthors = Akhigbe T, Zolnourian A, Bulters D | title = Compliance of systematic reviews articles in brain arteriovenous malformation with PRISMA statement guidelines: Review of literature | journal = Journal of Clinical Neuroscience | volume = 39 | pages = 45–48 | date = May 2017 | pmid = 28246008 | doi = 10.1016/j.jocn.2017.02.016 | s2cid = 27738264 }}{{cite journal | vauthors = Lee SY, Sagoo H, Farwana R, Whitehurst K, Fowler A, Agha R | title = Compliance of systematic reviews in ophthalmology with the PRISMA statement | journal = BMC Medical Research Methodology | volume = 17 | issue = 1 | pages = 178 | date = December 2017 | pmid = 29281981 | pmc = 5745614 | doi = 10.1186/s12874-017-0450-1 | doi-access = free }}{{cite journal | vauthors = E JY, Saldanha IJ, Canner J, Schmid CH, Le JT, Li T | title = Adjudication rather than experience of data abstraction matters more in reducing errors in abstracting data in systematic reviews | journal = Research Synthesis Methods | volume = 11 | issue = 3 | pages = 354–362 | date = May 2020 | pmid = 31955502 | doi = 10.1002/jrsm.1396 | s2cid = 210829764 }} A host of studies have identified weaknesses in the rigour and reproducibility of search strategies in systematic reviews.{{cite journal | vauthors = Koffel JB, Rethlefsen ML | title = Reproducibility of Search Strategies Is Poor in Systematic Reviews Published in High-Impact Pediatrics, Cardiology and Surgery Journals: A Cross-Sectional Study | journal = PLOS ONE | volume = 11 | issue = 9 | pages = e0163309 | date = 2016-09-26 | pmid = 27669416 | pmc = 5036875 | doi = 10.1371/journal.pone.0163309 | veditors = Thombs BD | doi-access = free | bibcode = 2016PLoSO..1163309K }}{{cite journal | vauthors = Yoshii A, Plaut DA, McGraw KA, Anderson MJ, Wellik KE | title = Analysis of the reporting of search strategies in Cochrane systematic reviews | journal = Journal of the Medical Library Association | volume = 97 | issue = 1 | pages = 21–29 | date = January 2009 | pmid = 19158999 | pmc = 2605027 | doi = 10.3163/1536-5050.97.1.004 }}{{cite journal | vauthors = Toews LC | title = Compliance of systematic reviews in veterinary journals with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) literature search reporting guidelines | journal = Journal of the Medical Library Association | volume = 105 | issue = 3 | pages = 233–239 | date = July 2017 | pmid = 28670210 | pmc = 5490700 | doi = 10.5195/jmla.2017.246 }}{{cite journal | vauthors = Mullins MM, DeLuca JB, Crepaz N, Lyles CM | title = Reporting quality of search methods in systematic reviews of HIV behavioral interventions (2000-2010): are the searches clearly explained, systematic and reproducible? | journal = Research Synthesis Methods | volume = 5 | issue = 2 | pages = 116–130 | date = June 2014 | pmid = 26052651 | pmc = 5861495 | doi = 10.1002/jrsm.1098 }}{{cite journal | vauthors = Briscoe S | title = A review of the reporting of web searching to identify studies for Cochrane systematic reviews | journal = Research Synthesis Methods | volume = 9 | issue = 1 | pages = 89–99 | date = March 2018 | pmid = 29065246 | doi = 10.1002/jrsm.1275 | s2cid = 206155997 }}{{cite journal | vauthors = Golder S, Loke Y, McIntosh HM | title = Poor reporting and inadequate searches were apparent in systematic reviews of adverse effects | journal = Journal of Clinical Epidemiology | volume = 61 | issue = 5 | pages = 440–448 | date = May 2008 | pmid = 18394536 | doi = 10.1016/j.jclinepi.2007.06.005 }} To remedy this issue, a new PRISMA guideline extension called PRISMA-S is being developed.{{cite journal | doi=10.1186/s13643-020-01542-z | doi-access=free | title=PRISMA-S: An extension to the PRISMA Statement for Reporting Literature Searches in Systematic Reviews | date=2021 | last1=Rethlefsen | first1=Melissa L. | last2=Kirtley | first2=Shona | last3=Waffenschmidt | first3=Siw | last4=Ayala | first4=Ana Patricia | last5=Moher | first5=David | last6=Page | first6=Matthew J. | last7=Koffel | first7=Jonathan B. | last8=Blunt | first8=Heather | last9=Brigham | first9=Tara | last10=Chang | first10=Steven | last11=Clark | first11=Justin | last12=Conway | first12=Aislinn | last13=Couban | first13=Rachel | last14=De Kock | first14=Shelley | last15=Farrah | first15=Kelly | last16=Fehrmann | first16=Paul | last17=Foster | first17=Margaret | last18=Fowler | first18=Susan A. | last19=Glanville | first19=Julie | last20=Harris | first20=Elizabeth | last21=Hoffecker | first21=Lilian | last22=Isojarvi | first22=Jaana | last23=Kaunelis | first23=David | last24=Ket | first24=Hans | last25=Levay | first25=Paul | last26=Lyon | first26=Jennifer | last27=McGowan | first27=Jessie | last28=Murad | first28=M. Hassan | last29=Nicholson | first29=Joey | last30=Pannabecker | first30=Virginia | journal=Systematic Reviews | volume=10 | issue=1 | page=39 | pmid=33499930 | pmc=7839230 | display-authors=1 }} Furthermore, tools and checklists for peer-reviewing search strategies have been created, such as the Peer Review of Electronic Search Strategies (PRESS) guidelines.{{cite journal | vauthors = McGowan J, Sampson M, Salzwedel DM, Cogo E, Foerster V, Lefebvre C | title = PRESS Peer Review of Electronic Search Strategies: 2015 Guideline Statement | journal = Journal of Clinical Epidemiology | volume = 75 | pages = 40–46 | date = July 2016 | pmid = 27005575 | doi = 10.1016/j.jclinepi.2016.01.021 | doi-access = free }}

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){{cite journal | vauthors = Shea BJ, Reeves BC, Wells G, Thuku M, Hamel C, Moran J, Moher D, Tugwell P, Welch V, Kristjansson E, Henry DA | display-authors = 6 | title = AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both | journal = BMJ | volume = 358 | pages = j4008 | date = September 2017 | pmid = 28935701 | pmc = 5833365 | doi = 10.1136/bmj.j4008 }}{{cite journal | vauthors = Shea BJ, Grimshaw JM, Wells GA, Boers M, Andersson N, Hamel C, Porter AC, Tugwell P, Moher D, Bouter LM | display-authors = 6 | title = Development of AMSTAR: a measurement tool to assess the methodological quality of systematic reviews | journal = BMC Medical Research Methodology | volume = 7 | issue = 1 | pages = 10 | date = February 2007 | pmid = 17302989 | pmc = 1810543 | doi = 10.1186/1471-2288-7-10 | doi-access = free }}{{cite journal | vauthors = Shea BJ, Hamel C, Wells GA, Bouter LM, Kristjansson E, Grimshaw J, Henry DA, Boers M | display-authors = 6 | title = AMSTAR is a reliable and valid measurement tool to assess the methodological quality of systematic reviews | journal = Journal of Clinical Epidemiology | volume = 62 | issue = 10 | pages = 1013–1020 | date = October 2009 | pmid = 19230606 | doi = 10.1016/j.jclinepi.2008.10.009 | s2cid = 5935312 | url = https://research.vu.nl/en/publications/ee9eadc9-eb7d-419c-a869-575260a0b800 }} and ROBIS (Risk Of Bias In Systematic reviews); however, these are not appropriate for all systematic review types.{{cite journal | vauthors = Whiting P, Savović J, Higgins JP, Caldwell DM, Reeves BC, Shea B, Davies P, Kleijnen J, Churchill R | display-authors = 6 | title = ROBIS: A new tool to assess risk of bias in systematic reviews was developed | journal = Journal of Clinical Epidemiology | volume = 69 | pages = 225–234 | date = January 2016 | pmid = 26092286 | pmc = 4687950 | doi = 10.1016/j.jclinepi.2015.06.005 }} Some recent peer-reviewed articles have carried out comparisons between AMSTAR 2 and ROBIS tools.{{Cite journal |last1=Perry |first1=R. |last2=Whitmarsh |first2=A. |last3=Leach |first3=V. |last4=Davies |first4=P. |date=2021-10-25 |title=A comparison of two assessment tools used in overviews of systematic reviews: ROBIS versus AMSTAR-2 |journal=Systematic Reviews |volume=10 |issue=1 |pages=273 |doi=10.1186/s13643-021-01819-x |doi-access=free |issn=2046-4053 |pmc=8543959 |pmid=34696810}}{{Cite journal |last1=Pieper |first1=Dawid |last2=Puljak |first2=Livia |last3=González-Lorenzo |first3=Marien |last4=Minozzi |first4=Silvia |date=April 2019 |title=Minor differences were found between AMSTAR 2 and ROBIS in the assessment of systematic reviews including both randomized and nonrandomized studies |url=https://pubmed.ncbi.nlm.nih.gov/30543911/ |journal=Journal of Clinical Epidemiology |volume=108 |pages=26–33 |doi=10.1016/j.jclinepi.2018.12.004 |issn=1878-5921 |pmid=30543911}}

The first publication that is now recognized as equivalent to a modern systematic review was a 1753 paper by James Lind, which reviewed all of the previous publications about scurvy.{{Cite journal |last1=Clarke |first1=Mike |last2=Chalmers |first2=Iain |date=August 2018 |title=Reflections on the history of systematic reviews |journal=BMJ Evidence-Based Medicine |language=en |volume=23 |issue=4 |pages=121–122 |doi=10.1136/bmjebm-2018-110968 |pmid=29921711 |s2cid=49311760 |issn=2515-446X|doi-access=free }} Systematic reviews appeared only sporadically until the 1980s, and became common after 2000. More than 10,000 systematic reviews are published each year.

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.{{cite journal |author= |date=November 1904 |title=Report on Certain Enteric Fever Inoculation Statistics |journal=British Medical Journal |publisher=British Medical Journal Publishing Group |volume=2 |issue=2288 |pages=1243–1246 |doi=10.1136/bmj.2.2288.1243 |pmc=2355479 |pmid=20761760 |s2cid=30331745}} 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".{{cite web |title=1.1.2 A brief history of Cochrane |url=https://community.cochrane.org/handbook-sri/chapter-1-introduction/11-cochrane/112-brief-history-cochrane |archive-url=https://web.archive.org/web/20190117070242/https://community.cochrane.org/handbook-sri/chapter-1-introduction/11-cochrane/112-brief-history-cochrane |archive-date=2019-01-17 |access-date=2019-02-24 |website=community.cochrane.org |language=en}} Critical appraisal and synthesis of research findings in a systematic way emerged in 1975 under the term 'meta analysis'.{{cite book |url=https://catalogue.nla.gov.au/Record/5363514 |title=Meta-Analysis of Research on the Relationship of Class-Size and Achievement. The Class Size and Instruction Project |vauthors=Glass GV, Smith ML |collaboration=Far West Lab. for Educational Research and Development, San Francisco, CA |date=1978 |publisher=Distributed by ERIC Clearinghouse |location=Washington, D.C.]}}{{cite web |title=History of Systematic Reviews |url=https://eppi.ioe.ac.uk/cms/Resources/EvidenceInformedPolicyandPractice/HistoryofSystematicReviews/tabid/68/Default.aspx |access-date=2019-02-24 |work=Evidence for Policy and Practice Information and Co-ordinating Centre (EPPI-Centre)}} Early syntheses were conducted in broad areas of public policy and social interventions, with systematic research synthesis applied to medicine and health.{{cite journal |vauthors=Lau J, Antman EM, Jimenez-Silva J, Kupelnick B, Mosteller F, Chalmers TC |date=July 1992 |title=Cumulative meta-analysis of therapeutic trials for myocardial infarction |journal=The New England Journal of Medicine |volume=327 |issue=4 |pages=248–254 |doi=10.1056/NEJM199207233270406 |pmid=1614465 |doi-access=free}} Inspired by his own personal experiences as a senior medical officer in prisoner of war camps, Archie Cochrane worked to improve the scientific method in medical evidence.{{cite book |url=https://www.worldcat.org/oclc/741462 |title=Effectiveness and efficiency: random reflections on health services |vauthors=Cochrane AL |date=1972 |publisher=Nuffield Provincial Hospitals Trust |isbn=0-900574-17-8 |location=[London] |oclc=741462 |archive-url=https://web.archive.org/web/20200916053459/https://www.nuffieldtrust.org.uk/files/2017-01/effectiveness-and-efficiency-web-final.pdf |archive-date=2020-09-16}} His call for the increased use of randomised controlled trials and systematic reviews led to the creation of The Cochrane Collaboration,{{cite journal |vauthors=Shah HM, Chung KC |date=September 2009 |title=Archie Cochrane and his vision for evidence-based medicine |journal=Plastic and Reconstructive Surgery |volume=124 |issue=3 |pages=982–988 |doi=10.1097/PRS.0b013e3181b03928 |pmc=2746659 |pmid=19730323}} 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.{{cite book |url=https://www.worldcat.org/oclc/778837501 |title=Testing treatments : better research for better healthcare |vauthors=Evans I, Thornton H, Chalmers I, Glasziou P |date=2011 |publisher=Pinter & Martin |isbn=978-1-905177-48-6 |edition=Second |location=London |oclc=778837501}}

• Critical appraisal
• Further research is needed
• Systematic searching
• Horizon scanning
• Literature review
• Living review
• Meta-analysis
• Metascience
• Peer review
• Review journal
• Generalized model aggregation (GMA)
• Umbrella review

{{Academic peer reviewed|Q99440266|doi-access=free}} STARDIT report Q101116128.

{{Reflist}}

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• [http://www.systematicreviewtools.com Systematic Review Tools] — Search and list of systematic review software tools
• [http://www.cochrane.org/ Cochrane Collaboration]
• MeSH: [https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=mesh&list_uids=68012196&dopt=Full Review Literature]—articles about the review process
• MeSH: [https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=mesh&list_uids=68016454&dopt=Full Review [Publication Type]] - limit search results to reviews
• [http://www.prisma-statement.org/ Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement] {{Webarchive|url=https://web.archive.org/web/20110727021816/http://www.prisma-statement.org/ |date=27 July 2011 }}, "an evidence-based minimum set of items for reporting in systematic reviews and meta-analyses"
• [http://www.equator-network.org/reporting-guidelines/prisma-scr/ PRISMA Extension for Scoping Reviews (PRISMA-ScR): Checklist and explanation]
• [https://cccrg.cochrane.org/animated-storyboard-what-are-systematic-reviews Animated Storyboard: What Are Systematic Reviews?] - Cochrane Consumers and Communication Group
• [https://sysrev.com/ Sysrev] - a free platform with open access systematic reviews.
• STARDIT - an open access data-sharing system to standardise the way that information about initiatives is reported.

{{Medical research studies}}

{{DEFAULTSORT:Systematic Review}}

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Category:Evidence-based practices

Category:Information science

Category:Meta-analysis

Category:Nursing research