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The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement, published in 2009, was designed to help systematic reviewers transparently report why the review was done, what the authors did, and what they found. Over the past decade, advances in systematic review methodology and terminology have necessitated an update to the guideline. The PRISMA 2020 statement replaces the 2009 statement and includes new reporting guidance that reflects advances in methods to identify, select, appraise, and synthesise studies. The structure and presentation of the items have been modified to facilitate implementation. In this article, we present the PRISMA 2020 27-item checklist, an expanded checklist that details reporting recommendations for each item, the PRISMA 2020 abstract checklist, and the revised flow diagrams for original and updated reviews.

The methods and results of systematic reviews should be reported in sufficient detail to allow users to assess the trustworthiness and applicability of the review findings. The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement was developed to facilitate transparent and complete reporting of systematic reviews and has been updated (to PRISMA 2020) to reflect recent advances in systematic review methodology and terminology. Here, we present the explanation and elaboration paper for PRISMA 2020, where we explain why reporting of each item is recommended, present bullet points that detail the reporting recommendations, and present examples from published reviews. We hope that changes to the content and structure of PRISMA 2020 will facilitate uptake of the guideline and lead to more transparent, complete, and accurate reporting of systematic reviews.

To ensure a systematic review is valuable to users, authors should prepare a transparent, complete, and accurate account of why the review was done, what they did (such as how studies were identified and selected) and what they found (such as characteristics of contributing studies and results of meta-analyses). [...]technological advances have enabled the use of natural language processing and machine learning to identify relevant evidence [22,23,24], methods have been proposed to synthesise and present findings when meta-analysis is not possible or appropriate [25,26,27], and new methods have been developed to assess the risk of bias in results of included studies [28, 29]. [...]the publishing landscape has transformed, with multiple avenues now available for registering and disseminating systematic review protocols [33, 34], disseminating reports of systematic reviews, and sharing data and materials, such as preprint servers and publicly accessible repositories. [...]extensions to the PRISMA 2009 statement have been developed to guide reporting of network meta-analyses [49], meta-analyses of individual participant data [50], systematic reviews of harms [51], systematic reviews of diagnostic test accuracy studies [52], and scoping reviews [53]; for these types of reviews we recommend authors report their review in accordance with the recommendations in PRISMA 2020 along with the guidance specific to the extension.

The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement, published in 2009, was designed to help systematic reviewers transparently report why the review was done, what the authors did, and what they found. Over the past decade, advances in systematic review methodology and terminology have necessitated an update to the guideline. The PRISMA 2020 statement replaces the 2009 statement and includes new reporting guidance that reflects advances in methods to identify, select, appraise, and synthesise studies. The structure and presentation of the items have been modified to facilitate implementation. In this article, we present the PRISMA 2020 27-item checklist, an expanded checklist that details reporting recommendations for each item, the PRISMA 2020 abstract checklist, and the revised flow diagrams for original and updated reviews.

High quality protocols facilitate proper conduct, reporting, and external review of clinical trials. However, the completeness of trial protocols is often inadequate. To help improve the content and quality of protocols, an international group of stakeholders developed the SPIRIT 2013 Statement (Standard Protocol Items: Recommendations for Interventional Trials). The SPIRIT Statement provides guidance in the form of a checklist of recommended items to include in a clinical trial protocol. This SPIRIT 2013 Explanation and Elaboration paper provides important information to promote full understanding of the checklist recommendations. For each checklist item, we provide a rationale and detailed description; a model example from an actual protocol; and relevant references supporting its importance. We strongly recommend that this explanatory paper be used in conjunction with the SPIRIT Statement. A website of resources is also available (www.spirit-statement.org). The SPIRIT 2013 Explanation and Elaboration paper, together with the Statement, should help with the drafting of trial protocols. Complete documentation of key trial elements can facilitate transparency and protocol review for the benefit of all stakeholders.

The SPIRIT 2013 Statement (Standard Protocol Items: Recommendations for Interventional Trials) provides a systematically developed checklist of minimum key items that should be detailed in a trial protocol.1 These recommendations were informed by two systematic reviews and a Delphi consensus process that involved key stakeholders who conduct, review, fund, and publish trials.13 An associated SPIRIT explanatory paper outlines the rationale and details for each checklist item, provides protocol examples, and cites relevant supporting evidence.14 By providing examples from actual protocols for every checklist item, the SPIRIT explanatory paper14 shows the feasibility of addressing every recommended item in the protocol and its appendices rather than solely in separate documents such as a statistical analysis plan or data monitoring committee charter.

Systematic reviews (SRs) have become increasingly important for informing clinical practice; however, little is known about the reporting characteristics and the quality of the SRs relevant to the practice of rehabilitation health professionals. The purpose of this study was to examine the reporting quality of a representative sample of published SRs on rehabilitation, focusing on the descriptive, reporting, and bias-related characteristics. A cross-sectional study was conducted by searching MEDLINE for aggregative and configurative SRs indexed in 2011 that focused on rehabilitation as restorative of functional limitations. Two reviewers independently screened and selected the SRs and extracted data using a 38-item data collection form derived from Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The data were analyzed descriptively. Eighty-eight SRs published in 59 journals were sampled. The median compliance with the PRISMA items was 17 (63%) out of 27 items (interquartile ratio=13-22 [48%-82%]). Two thirds of the SRs (n=66) focused on interventions for which efficacy is best addressed through a randomized controlled trial (RCT) design, and almost all of these SRs included RCTs (63/66 [95%]). More than two thirds of the SRs assessed the quality of primary studies (74/88 [84%]). Twenty-eight reviews (28/88 [32%]) meta-analyzed the results for at least one outcome. One half of the SRs reported positive statistically significant findings (46%), whereas a detrimental result was present only in one review. This sample of SRs in the rehabilitation field showed heterogeneous characteristics and a moderate quality of reporting. Poor control of potential source of bias might be improved if more widely agreed-upon evidence-based reporting guidelines will be actively endorsed and adhered to by authors and journals.

The funders had no role in considering the study design or in the collection, analysis, interpretation of data, writing of the report, or decision to submit the article for publication. Competing interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: EL is head of research for the BMJ; MJP is an editorial board member for PLOS Medicine; ACT is an associate editor and MJP, TL, EMW, and DM are editorial board members for the Journal of Clinical Epidemiology; DM and LAS were editors in chief, LS, JMT, and ACT are associate editors, and JG is an editorial board member for Systematic Reviews. [...]technological advances have enabled the use of natural language processing and machine learning to identify relevant evidence,[22–24] methods have been proposed to synthesise and present findings when meta-analysis is not possible or appropriate,[25–27] and new methods have been developed to assess the risk of bias in results of included studies. Summary points * To ensure a systematic review is valuable to users, authors should prepare a transparent, complete, and accurate account of why the review was done, what they did, and what they found * The PRISMA 2020 statement provides updated reporting guidance for systematic reviews that reflects advances in methods to identify, select, appraise, and synthesise studies * The PRISMA 2020 statement consists of a 27-item checklist, an expanded checklist that details reporting recommendations for each item, the PRISMA 2020 abstract checklist, and revised flow diagrams for original and updated reviews * We anticipate that the PRISMA 2020 statement will benefit authors, editors, and peer reviewers of systematic reviews, and different users of reviews, including guideline developers, policy makers, healthcare providers, patients, and other stakeholders Development of PRISMA 2020 A complete description of the methods used to develop PRISMA 2020 is available elsewhere.

Background Recent evidence has highlighted deficiencies in clinical trial protocols, having implications for many groups. Existing guidelines for randomized clinical trial (RCT) protocol content vary substantially and most do not describe systematic methodology for their development. As one of three prespecified steps for the systematic development of a guideline for trial protocol content, the objective of this study was to conduct a three-round Delphi consensus survey to develop and refine minimum content for RCT protocols. Methods Panellists were identified using a multistep iterative approach, met prespecified minimum criteria and represented key stakeholders who develop or use clinical trial protocols. They were asked to rate concepts for importance in a minimum set of items for RCT protocols. The main outcome measures were degree of importance (scale of 1 to 10; higher scores indicating higher importance) and level of consensus for items. Results were presented as medians, interquartile ranges, counts and percentages. Results Ninety-six expert panellists participated in the Delphi consensus survey including trial investigators, methodologists, research ethics board members, funders, industry, regulators and journal editors. Response rates were between 88 and 93% per round. Overall, panellists rated 63 of 88 concepts of high importance (of which 50 had a 25 th percentile rating of 8 or greater), 13 of moderate importance (median 6 or 7) and 12 of low importance (median less than or equal to 5) for minimum trial protocol content. General and item-specific comments and subgroup results provided valuable insight for further discussions. Conclusions This Delphi process achieved consensus from a large panel of experts from diverse stakeholder groups on essential content for RCT protocols. It also highlights areas of divergence. These results, complemented by other empirical research and consensus meetings, are helping guide the development of a guideline for protocol content.

High quality protocols facilitate proper conduct, reporting, and external review of clinical trials. However, the completeness of trial protocols is often inadequate. To help improve the content and quality of protocols, an international group of stakeholders developed the SPIRIT 2013 Statement (Standard Protocol Items: Recommendations for Interventional Trials). The SPIRIT Statement provides guidance in the form of a checklist of recommended items to include in a clinical trial protocol. This SPIRIT 2013 Explanation and Elaboration paper provides important information to promote full understanding of the checklist recommendations. For each checklist item, we provide a rationale and detailed description; a model example from an actual protocol; and relevant references supporting its importance. We strongly recommend that this explanatory paper be used in conjunction with the SPIRIT Statement. A website of resources is also available (www.spirit-statement.org). The SPIRIT 2013 Explanation and Elaboration paper, together with the Statement, should help with the drafting of trial protocols. Complete documentation of key trial elements can facilitate transparency and protocol review for the benefit of all stakeholders.