PROSPERO registration is the process of submitting your systematic review protocol to the international prospective register of systematic reviews before screening begins. This PROSPERO registration guide walks you through every field, explains timing requirements, and shows you how to complete a strong registration that demonstrates methodological rigor to journals and peer reviewers.
PROSPERO is the international prospective register of systematic reviews, maintained by the Centre for Reviews and Dissemination (CRD) at the University of York, funded by NIHR. Researchers register their systematic review protocol, including research question PICO, search strategy, eligibility criteria, and analysis plan, before screening begins, to prevent outcome-switching and demonstrate methodological transparency.
We have completed hundreds of PROSPERO registrations, the most common issue we see is researchers registering after screening has already begun, which triggers the retrospective flag and weakens the credibility of an otherwise sound protocol. This guide gives you the field-by-field detail you need to get it right the first time.
What Is PROSPERO?
The purpose of protocol registration is straightforward: by recording your research question, methods, and analysis plan before you see the data, you demonstrate that your conclusions were not shaped by results. This transparency is the foundation of credible evidence synthesis. Every evidence synthesis protocol, whether for a systematic review, scoping review, or rapid review, benefits from prospective registration.
PROSPERO currently holds over 500,000 registered protocols from researchers worldwide. Each registration receives a unique identifier (CRD42XXXXXXX) that you cite in your manuscript abstract, methods section, and PRISMA flow diagram. Journals, peer reviewers, and guideline developers use this identifier to verify that your review was planned prospectively.
| Feature | PROSPERO | OSF Preregistration | Cochrane CDSR |
|---|---|---|---|
| Focus | Health-related systematic reviews | Any study type, any discipline | Cochrane systematic reviews only |
| Cost | Free | Free | Requires Cochrane author team |
| Scope | Protocols only | Protocols + data + materials | Full protocol + completed review |
| Approval time | 2–5 business days | Immediate | Months (editorial process) |
| Unique ID | CRD42XXXXXXX | DOI-based | Cochrane DOI |
For a complete overview of the protocol development process that feeds into registration, see our systematic review protocol guide.
Why You Should Register on PROSPERO
PROSPERO registration prevents outcome-switching, demonstrates methodological rigor to journals, and reduces duplication of effort across the research community. A systematic review requires protocol registration to establish credibility before results are known.
Prevents outcome-switching. When you register your primary outcomes, analysis methods, and eligibility criteria before screening, you create a public record that reviewers can check. If your published review deviates from the registered protocol without documented amendments, peer reviewers will flag it, and rightly so. Prospective registration eliminates the suspicion that you adjusted your methods after seeing which results looked favorable.
Demonstrates rigor to journals. Many high-impact journals, including BMJ, The Lancet, JAMA, and all Cochrane publications, either require or strongly recommend PROSPERO registration. Submitting a manuscript with a PROSPERO ID signals to editors that your review followed established methodological standards. Even journals that do not mandate registration view it favorably during peer review.
Reduces duplication. Before starting a new systematic review, researchers are expected to search PROSPERO CRD for ongoing reviews on the same topic. The ability to register systematic review protocols publicly is one of PROSPERO's most important contributions to research transparency. Your registration helps the broader community avoid duplicating effort, and it helps you identify potential collaborators working on similar questions.
Strengthens your peer review defense. When reviewers question your methodology, pointing to a prospectively registered protocol is one of the strongest responses available. The protocol was locked in before you had results, that is difficult to argue with.
For guidance on structuring the research question that anchors your registration, see our our guide to pico framework guide.
When to Register on PROSPERO
You should register your systematic review on PROSPERO after finalizing your protocol but before beginning title and abstract screening. This is the optimal window, your methods are set, but you have not yet been exposed to study results that could bias your approach.
Before screening begins (prospective). The gold standard. CRD explicitly designed PROSPERO for prospective registration, recording your plan before you encounter the evidence. Registrations submitted before screening carry no flags or caveats.
After screening has started (retrospective). If you register after screening has begun, CRD will flag your registration as retrospective. This flag appears publicly on your PROSPERO record and in any exports. While retrospective registration is still better than no registration at all, it weakens your methodological credibility because it cannot rule out the possibility that results influenced your protocol decisions. PROSPERO registration should occur before study screening begins, retrospective registrations are flagged by CRD, indicating that the protocol was finalized after seeing study results (CRD, University of York).
Cochrane reviews. If you are conducting a Cochrane systematic review, your protocol is registered through the Cochrane Database of Systematic Reviews (CDSR) rather than PROSPERO. Cochrane has its own editorial and registration process. Do not register a Cochrane review on PROSPERO.
Data extraction or later. If you have already completed data extraction or analysis before considering registration, PROSPERO will still accept your submission, but the retrospective flag will be prominent. At this stage, registration serves as a record rather than a prospective commitment.
Want your PROSPERO registration handled professionally? Our team writes and submits complete protocol registrations, including search strategy documentation and methodology sections that satisfy reviewers. arrange a free research project discussion, or see our custom systematic review services assistance.
