PRISMA 2020 replaced the 2009 statement and is now expected by most journals publishing systematic reviews. Submitting without a completed checklist is a common cause of an immediate return.
What PRISMA is, and is not
It is a reporting guideline. It tells you what must be described so a reader can appraise and reproduce the work. It does not tell you how to conduct the review, and completing it does not make a flawed method sound.
What changed in 2020
- Expanded from 27 to 27 items with sub-items, restructured to match how reviews are actually conducted
- Explicit reporting of automation tools used in screening
- Reporting of certainty assessment, typically GRADE
- A new flow diagram version for updated reviews
- A separate 12-item checklist for abstracts
- Greater emphasis on data availability and the sharing of extraction files
The flow diagram
Four stages: identification, screening, eligibility, inclusion. Every number must reconcile — records identified, duplicates removed, records screened, full texts assessed, studies included, with reasons given for every full-text exclusion.
The items authors most often miss
- Item 7, the full search strategy. A summary is not sufficient; the complete string for at least one database must be reproduced.
- Item 5, the eligibility criteria. Must be stated as they were pre-specified, not as they ended up.
- Item 11, risk of bias. Requires who assessed, how many assessors, and how disagreements were resolved.
- Item 13d, heterogeneity. Must state how it was assessed, not just report the result.
- Item 22, certainty of evidence. Frequently omitted entirely.
- Item 27, data availability. Where the protocol, extraction data and code can be found.
Practical advice
Complete the checklist as you write, not afterwards. Fill in the page number for each item as you go, and submit it as a supplementary file. If an item genuinely does not apply, write not applicable and explain why rather than leaving it blank.
PRISMA is one of several reporting guidelines. Our guide to CONSORT, STROBE, PRISMA, CARE and STARD explains which applies to which design.