What is registration?

Registration in PROSPERO involves the submission and publication of key information about the design and conduct of a systematic review. Applications are assessed to ensure that they fall within scope and that the required data have been provided. No quality assessment or peer review is involved. Records are published on an open access electronic database.

Registration information can be amended should plans change. All such changes are published and an audit trail of previous versions made available in the public record.

Registration records are permanent and registrants are asked to provide links to subsequent reports and publications. The record can be ‘re-activated’ when a completed review is updated.

PROSPERO assigns each registered review with a unique registration number. This number can be cited in publications and reports to provide the link between the planned and completed review, as recommended by PRISMA 2009 and many publishers.

Why is prospective registration of systematic reviews important?

Registration provides transparency in the review process. It helps counter publication bias by providing a permanent record of prospectively registered reviews, irrespective of whether they are eventually published or not. It helps safeguard against reporting biases by revealing any differences between the methods or outcomes reported in the published review and those planned in the registered protocol. This should improve quality and increase confidence that policy or practice informed by the findings of a systematic review is drawing on best-quality evidence. Registration allows those commissioning or planning reviews to identify whether there are any reviews already underway that address their topic of interest. This helps avoid unintended and economically wasteful duplication of effort.

PROSPERO assists:

  • Researchers by allowing them to comply with PRISMA, providing a public record of their planned methods and raising awareness of their review. Use of the unique registration number allows them to track subsequent use of their review and monitor impact.
  • Commissioners and funders by allowing them to identify ongoing and unpublished reviews addressing their topic of interest, thereby helping avoid unplanned duplication.
  • Peer reviewers by allowing comparison of manuscript findings with the review protocol.
  • Journal Editors by providing a safeguard against reporting biases and providing access to key protocol features that they can utilise in the peer review process, where appropriate.
  • Guideline developers by providing information about forthcoming reviews which may assist in planning and timing of guideline development.
  • The public by providing free and open access to information about ongoing systematic reviews, by encouraging transparency in the systematic review process, by helping ensure that health and social care decisions that may affect them are known to be based on good quality systematic review evidence, and by helping to avoid wasting money on unintended duplication of effort.

Reducing unplanned duplication of systematic reviews

PROSPERO's single searchable listing of on-going systematic reviews enables commissioners and researchers to check whether there is an existing review that addresses their topic of interest, before planning a new review. The aim is to reduce unplanned duplication of reviews and promote efficient use of resources. The NIHR HTA Programme demonstrated success for this aim when they decided not to commission research on restricted elimination diet in Attention Deficit-Hyperactivity Disorder when PROSPERO revealed that an overlapping research project was already in progress.

However, there are appropriate and valuable reasons for undertaking independent replication of reviews, diverse ways of answering specific questions, and advances in knowledge can stem from looking at things from a different angle. We do not feel it would be appropriate, or indeed possible, for us to regulate submissions with similar titles and therefore do no attempt to do so.

PROSPERO relies on the integrity of researchers for the accuracy of the data supplied and by providing access to details of ongoing reviews, facilitates appropriate planning and justification of reviews. Each published record contains the anticipated start date, the anticipated completion date and the date on which the record was accepted for publication on PROSPERO. This enables users to assess for themselves the chronology of records entered on the database.

Are there risks from registration?

Some researchers have expressed concern that titles and protocol details registered in PROSPERO could be copied and used by other researchers. Conversely others have raised concerns about reviews being registered but never completed, discouraging others from addressing the same topic. PROSPERO does not preclude registration of duplicate reviews as this would be counter to the open and collaborative aims of registration. We take a pragmatic approach and trust to the integrity of researchers.

All records are permanent and contain the date of initial registration on PROSPERO, the anticipated start date and the anticipated completion date. It is inevitable that some reviews will take longer than expected, and a facility to amend these dates is provided. Every change is documented in the public archive such that users can consider whether the delays appear appropriate and justified. All records also contain the name and email address of the named contact for the review, who can be approached for information about progress. This all means that users can make their own judgements about the likelihood of completion of registered reviews, degree of overlap with their own review topic and whether duplication might be beneficial. Highlighting areas of overlapping interest may even generate collaborative approaches.

Commissioners and funders or membership organisations may use information from PROSPERO to help decide what research is undertaken by whom within their funding stream or organisation. PROSPERO does not have, or seek to have, any mandate to regulate the systematic review process.