PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) is an evidence-based reporting standard that tells authors what to disclose when they publish a systematic review. The current version, PRISMA 2020 (Page et al.), pairs a 27-item checklist with a four-phase flow diagram so that readers can judge a review’s methods, completeness and reproducibility.
What PRISMA is — and what it is not
PRISMA is a reporting guideline, not a method for conducting a review. It does not tell you how to design a search strategy, appraise risk of bias or pool effect sizes; it tells you how to report the work you did so another team could appraise or repeat it. That distinction matters. A methodologically weak review can still be PRISMA-compliant if it reports its weaknesses transparently, and a strong review can fail PRISMA if it omits required items. PRISMA sits alongside conduct frameworks such as the Cochrane Handbook, which governs how the review is performed.
The 2020 update
The original PRISMA Statement appeared in 2009. The 2020 revision modernised it to reflect advances in synthesis methods and terminology over the intervening decade: clearer guidance on reporting search strategies for every database, automation tools, study selection, and methods for assessing certainty of evidence such as GRADE. The flow diagram was redrawn to accommodate reviews that update an earlier search and to record records identified through methods other than database searching, such as citation chasing and contact with experts.
The checklist and the flow diagram
The checklist’s 27 items map onto the standard structure of a review — title, abstract, introduction, methods, results, discussion and other information. Each item names a specific thing to report: the registration and protocol, eligibility criteria, the full electronic search strategy, the synthesis methods, and any deviations from the protocol. PRISMA 2020 also provides an expanded abstract checklist so that even readers who never reach the full text can assess the review’s scope.
The flow diagram is PRISMA’s most recognisable artefact. It tracks records through four phases — identification, screening, eligibility and inclusion — and reports, at each stage, how many records were found, how many were removed as duplicates, how many were excluded and why. A complete diagram makes the path from thousands of search hits to a handful of included studies auditable.
What PRISMA standardises
| Section | Representative reporting items |
|---|---|
| Methods | Eligibility criteria, information sources, full search strategy, selection process, data items, risk-of-bias assessment, synthesis methods |
| Results | Study selection (flow diagram), study characteristics, risk-of-bias results, results of syntheses, certainty of evidence |
| Other | Registration and protocol, support and funding, competing interests, availability of data and code |
Who maintains PRISMA
PRISMA is one of the flagship guidelines curated by the EQUATOR Network, the international initiative that catalogues reporting guidelines across study designs. EQUATOR hosts the checklist, the explanation-and-elaboration document and the various PRISMA extensions — for scoping reviews, network meta-analyses, abstracts, individual-patient-data reviews and search reporting. Because EQUATOR maintains the canonical record, authors should download the current materials there rather than copying older versions from secondary sources.
For a definition-first reference to PRISMA and related terms, see the CASRAI dictionary, and read our overview of reporting guidelines and the EQUATOR Network. Authors preparing a manuscript can also consult our guidance for authors and our look at next-generation systematic reviews.
Frequently asked questions
Is PRISMA only for meta-analyses?
No. PRISMA applies to systematic reviews whether or not they include a meta-analysis. The statistical pooling step is optional; the structured, transparent reporting of the review process is not. A qualitative or narrative synthesis still follows PRISMA. See our explainer on the difference between a systematic review and a meta-analysis.
Does following PRISMA guarantee a high-quality review?
No. PRISMA improves transparency, which makes quality assessable, but it cannot fix flawed methods. Critical-appraisal and risk-of-bias tools serve that purpose. Complete reporting and sound conduct are complementary, not substitutes.
Where should a review be registered?
PRISMA asks authors to report registration. Many reviewers register a protocol in a public registry before screening begins, and PRISMA 2020 expects the registration number and the protocol’s availability to be stated so reviewers and editors can check for deviations.
What is the difference between PRISMA and CONSORT?
PRISMA governs the reporting of systematic reviews; CONSORT governs the reporting of individual randomised controlled trials. Both are EQUATOR guidelines, but they apply at different points of the evidence pipeline.
