If you write up a systematic review without following PRISMA, two things happen. Reviewers ask why, and you spend the revision reconstructing details you should have recorded months earlier. PRISMA is the standard that tells you what a systematic review must report, and the 2020 version is the one to use. The 2009 statement it replaced should no longer be followed.
Understanding PRISMA is not just a writing-up task. Planning your review around it from the start means you record the right things as you go, rather than scrambling for them at the end.
PRISMA stands for Preferred Reporting Items for Systematic reviews and Meta-Analyses. It is a reporting guideline: it tells you what to report in a systematic review, not how to conduct one. The current version, PRISMA 2020, replaced the original 2009 statement to reflect advances in review methods.
Its core is a 27-item checklist organized into seven sections, accompanied by a 12-item checklist for abstracts and a flow diagram that tracks studies from identification to inclusion. A family of extensions adapts it to specific review types.
This distinction trips people up, so it is worth stating plainly. PRISMA does not tell you how to run a systematic review. It does not tell you how many databases to search, which risk-of-bias tool to use, or when to run a meta-analysis. It tells you what to write down once you have done those things, so that a reader can see exactly what you did and, in principle, reproduce it.
That means PRISMA is not a quality-assessment tool for judging whether a review was well conducted, and it is not a method. A review can follow PRISMA to the letter and still be a poor review if the underlying methods were weak. What PRISMA guarantees is transparency, not quality. Transparency is what lets a reader judge the quality for themselves.
The practical implication: use PRISMA as a planning aid, not just a submission checklist. If you know from the start that you will need to report your full search strategy, your exclusion reasons, and your risk-of-bias judgments, you will record them as you work instead of trying to reconstruct them later.
PRISMA 2020 is an update, not a reinvention, but the changes matter. The 2009 statement predated a decade of developments in how reviews are conducted and reported, and the update reflects those.
The checklist still has 27 items, but they were restructured and expanded, with several items now broken into sub-items to capture detail the original glossed over. The guidance around searching, study selection, and synthesis was strengthened to reflect current methods. The flow diagram was revised, including new versions that separate studies found through databases and registers from those found through other methods such as citation searching. And the wording throughout was updated for consistency and clarity.
The headline point for anyone starting a review today: use PRISMA 2020. The 2009 statement is retired, and reporting against it signals that you are working from outdated guidance.
PRISMA 2020 is best understood as three pieces that work together.
The 27-item checklist. The main instrument. It lists what to report across seven sections of the manuscript: title, abstract, introduction, methods, results, discussion, and other information (such as funding and conflicts of interest). Some items have sub-items. This is the backbone of PRISMA compliance.
The abstract checklist. A separate 12-item checklist for what to report in the abstract itself, since many readers and screeners see only the abstract. It ensures the abstract conveys the essential elements of the review in miniature.
The flow diagram. A visual that tracks the flow of studies through the review, from the number identified, through the numbers screened and excluded, down to the number finally included, with reasons for exclusion. PRISMA provides template versions for original and updated reviews, and versions that account for studies found through methods beyond database searching.
| Component | What it covers | Size |
|---|---|---|
| Main checklist | What to report across the whole manuscript | 27 items, 7 sections |
| Abstract checklist | What to report in the abstract | 12 items |
| Flow diagram | The flow of studies from identification to inclusion | Template, adaptable |
PRISMA 2020 is built for standard systematic reviews of interventions. A family of extensions adapts the same philosophy to other contexts. The main ones:
PRISMA-P for systematic review protocols, a 17-item checklist for what to report when you write your plan.
PRISMA-ScR for scoping reviews, adapting the items to the mapping purpose of a scoping review.
PRISMA-S for search reporting, a 16-item checklist focused entirely on documenting the literature search reproducibly.
PRISMA for Abstracts, the 12-item abstract checklist mentioned above.
PRISMA-NMA for reviews incorporating network meta-analysis, adding items specific to comparing multiple interventions.
There are others for diagnostic accuracy, individual participant data, and more. The principle is constant across all of them: report enough that a reader can see and reproduce what you did.
Read the checklist before you start, not after you finish. Each item is something you will need to report, which means it is something you should record as you go. The full search strategy, the number of records at each stage, the reasons for full-text exclusions, and the risk-of-bias judgments are all far easier to capture in the moment than to reconstruct.
When you write up, work through the checklist item by item and note where in your manuscript each is addressed, which is exactly what journals expect you to submit alongside the review. Build the flow diagram from your actual screening records rather than from numbers assembled at the end, since numbers that do not reconcile are a common and avoidable flag.
Consult the PRISMA 2020 explanation and elaboration document when an item is unclear. It gives the rationale and worked examples for each item, and it is the authoritative companion to the checklist.
What is PRISMA 2020? The current version of the PRISMA reporting guideline for systematic reviews. It consists of a 27-item checklist, a 12-item abstract checklist, and a flow diagram, and it replaced the PRISMA 2009 statement.
Is PRISMA a method for conducting a review? No. PRISMA is a reporting guideline. It tells you what to report, not how to conduct the review. It is also not a tool for judging a review's quality.
What is the difference between PRISMA 2009 and 2020? PRISMA 2020 restructured and expanded the items, strengthened guidance on searching and synthesis, and revised the flow diagram. The 2009 statement is retired and should no longer be used.
How many items are in the PRISMA checklist? The main PRISMA 2020 checklist has 27 items across seven sections, some with sub-items. The separate abstract checklist has 12 items.
Do I have to use PRISMA? Many journals require it for systematic reviews, and it is standard good practice. Using it demonstrates transparent, complete reporting.
PRISMA 2020 is the reporting standard for systematic reviews: a 27-item checklist, a 12-item abstract checklist, and a flow diagram, supported by a family of extensions for specific review types. It governs what you report, not how you conduct the review, and it is not a measure of quality. What it delivers is transparency, the ability for a reader to see exactly what you did.
Use the 2020 version, plan your review around the checklist from the start, and build your flow diagram from real screening records. Doing so turns PRISMA from an end-of-project chore into a structure that keeps your review reportable throughout.
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