BMJ 2015;349:g7647 doi: 10.1136/bmj.g7647 (Published 2 January 2015) Page 1 of 25 Research Methods & Reporting BMJ: first published as 10.1136/bmj.g7647 on 2 January 2015. Downloaded from RESEARCH METHODS & REPORTING Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015: elaboration and explanation OPEN ACCESS 1 1 2 3 4 Larissa Shamseer , David Moher , Mike Clarke , Davina Ghersi , Alessandro Liberati (deceased) , 5 6 7 Mark Petticrew , Paul Shekelle , Lesley A Stewart , the PRISMA-P Group 1Ottawa Hospital Research Institute and University of Ottawa, Canada; 2Queen’s University Belfast, Ireland; 3National Health and Medical Research Council, Australia; 4University of Modena, Italy; 5London School of Hygiene and Tropical Medicine, UK; 6Southern California Evidence-based Practice Center, USA; 7Centre for Reviews and Dissemination, University of York, UK Dedication: The PRISMA-P 2015 initiative is dedicated to our colleague encouraged to make use of PRISMA-P when drafting and appraising Alessandro Liberati (1954–2012), who passed away while PRISMA-P review protocols. 2015 was under development and whose contributions to this work were http://www.bmj.com/ invaluable. Introduction Abstract Systematic reviews hold a unique place in healthcare. They help Protocols of systematic reviews and meta-analyses allow for planning form the basis for developing practice guidelines and they and documentation of review methods, act as a guard against arbitrary provide information on gaps in knowledge, thus informing future decision making during review conduct, enable readers to assess for research efforts. This information is relevant to stakeholders the presence of selective reporting against completed reviews, and, across the health system. The rigour and trustworthiness of on 25 September 2021 by guest. Protected copyright. when made publicly available, reduce duplication of efforts and potentially systematic reviews is, in large part, based on the a priori prompt collaboration. Evidence documenting the existence of selective planning and documentation of a methodical approach to reporting and excessive duplication of reviews on the same or similar conduct (that is, a protocol). topics is accumulating and many calls have been made in support of A systematic review protocol is important for several reasons: the documentation and public availability of review protocols. Several (1) it allows systematic reviewers to plan carefully and thereby efforts have emerged in recent years to rectify these problems, including anticipate potential problems; (2) it allows reviewers to explicitly development of an international register for prospective reviews document what is planned before they start their review, (PROSPERO) and launch of the first open access journal dedicated to enabling others to compare the protocol and the completed the exclusive publication of systematic review products, including review (that is, to identify selective reporting), to replicate protocols (BioMed Central’s Systematic Reviews). Furthering these review methods if desired, and to judge the validity of planned efforts and building on the PRISMA (Preferred Reporting Items for methods; (3) it prevents arbitrary decision making with respect Systematic Reviews and Meta-analyses) guidelines, an international to inclusion criteria and extraction of data; and (4) it may reduce group of experts has created a guideline to improve the transparency, duplication of efforts and enhance collaboration, when available. accuracy, completeness, and frequency of documented systematic Various international organizations such as the Cochrane and review and meta-analysis protocols—PRISMA-P (for protocols) 2015. Campbell Collaborations and the Agency for Healthcare The PRISMA-P checklist contains 17 items considered to be essential Research and Quality (AHRQ) regularly require and publish and minimum components of a systematic review or meta-analysis protocols. However, outside of such organizations, few protocols protocol. are published in traditional journals and most reports of This PRISMA-P 2015 Explanation and Elaboration paper provides completed reviews (89%) do not mention working from a readers with a full understanding of and evidence about the necessity protocol1 (2014 update under way). Many experts have called of each item as well as a model example from an existing published for improved documentation and availability of review protocols. protocol. This paper should be read together with the PRISMA-P 2015 In response, experts (some of whom are authors on this statement. Systematic review authors and assessors are strongly document) launched an international, prospective register for systematic review protocols (PROSPERO, www.crd.york.ac. Correspondence to: L Shamseer [email protected] No commercial reuse: See rights and reprints http://www.bmj.com/permissions Subscribe: http://www.bmj.com/subscribe BMJ 2015;349:g7647 doi: 10.1136/bmj.g7647 (Published 2 January 2015) Page 2 of 25 RESEARCH METHODS & REPORTING uk/prospero/) through the Centre for Reviews and Dissemination Development of PRISMA-P at the University of York (UK) in February 2011, in which more BMJ: first published as 10.1136/bmj.g7647 on 2 January 2015. Downloaded from The PRISMA-P checklist is based on elements from the than 5000 systematic review protocols from 69 countries have 11 12 been registered as of December 2014. In February 2012, the PROSPERO register, the PRISMA checklist, SPIRIT first open access journal to exclusively publish systematic review (Standard Protocol Items: Recommendations for Interventional Trials) checklist items,13 and Standard 2.6 from the Institute of products including protocols (BioMed Central’s Systematic 14 Reviews) was launched, in which 142 protocols have been Medicine’s Standards for Systematic Reviews. A detailed description of the steps undertaken during PRISMA-P published (June 2014). Outside of select systematic review 15 organizations, little to no general guidance exists for preparing development can be found in the PRISMA-P Statement paper. review protocols. The process follows general recommendations of the EQUATOR (Enhancing the Quality and Transparency of health Research) Network on how to develop a reporting guideline, of Selective reporting 16 which one fundamental part is a consensus process. An Arguably one of the most important functions of systematic in-person consensus meeting of international experts was held review protocols is their role as a documentation of planned in June 2011 in Rockville, MD, USA, to develop and refine review methods, outcomes, and analyses that can be compared PRISMA-P checklist items. All related guidance documents with completed reviews to detect whether unintended and have undergone iterative revision within the PRISMA-P Group undocumented changes were made. Bias related to selective listed at the end of this document; members of the PRISMA-P reporting of outcomes (that is, when reporting is related to the Group contributed to the writing and identifying relevant statistical significance or direction of effect estimate) is a examples in this document. problem in clinical research. This is a well documented phenomenon in clinical trials,2-7 and similar findings are starting PRISMA-P checklist to emerge for systematic reviews (see item 13 for full discussion).8-10 When reviewers selectively choose which The final PRISMA-P checklist contains 17 numbered items (26 information to include in a report based on the direction and sub-items) that should be described, at minimum, in protocols significance of findings, they risk biasing the evidence base on of systematic reviews and meta-analyses (table 2⇓). The which healthcare decisions and policies are made. checklist is divided into three main sections: administrative information, introduction, and methods. Readers familiar with Further to recent efforts to increase the documentation and PRISMA will observe that wording of the PRISMA-P checklists availability of review protocols, the next logical step is the has, where possible, been harmonized with PRISMA checklist development of a set of standards that should be included in a items, at least 13 of which are overlapping with PRISMA-P. review protocol. A well described protocol may facilitate and We anticipate this will aid authors in transitioning their http://www.bmj.com/ enhance the detection of undocumented changes to review systematic review protocols prepared in accordance with methodology; it also may allow readers to gauge the potential PRISMA-P into full text, PRISMA-compliant, systematic review impact of such changes as well as selective reporting of reports. information on review findings. To that end, a reporting guideline for systematic review PRISMA-P Elaboration and Explanation protocols, an extension of the PRISMA (Preferred Items for Reporting Systematic Reviews and Meta-analyses) statement The format of this document follows that of previously on 25 September 2021 by guest. Protected copyright. has been developed for protocols (PRISMA-P) and is described established reporting guidelines such as the PRISMA in detail in this paper. Explanation and Elaboration document17; it aims to provide readers with comprehensive explanations and evidence based Scope of PRISMA-P rationales for each checklist item. Examples of good reporting for each checklist item have been identified from existing PRISMA-P is intended to guide the development of protocols systematic review and meta-analysis protocols