Registering a systematic review is an important process that provides significant benefits to individual researchers and the academic community. The following are several of those benefits (https://www.crd.york.ac.uk/PROSPERO/#aboutpage):
Provides a comprehensive listing of systematic reviews registered at inception
Counters publication bias
Safeguards against reporting biases by revealing any differences between the methods or outcomes reported in the published review and those planned in the registered protocol
Identifies whether there are any reviews already underway that address the topic of interest
PROSPERO is the most well-known systematic review registry, but there are others.
PROSPERO is an international database of prospectively registered systematic reviews in health and social care, welfare, public health, education, crime, justice, and international development, where there is a health related outcome. Key features from the review protocol are recorded and maintained as a permanent record. PROSPERO aims to provide a comprehensive listing of systematic reviews registered at inception to help avoid duplication and reduce opportunity for reporting bias by enabling comparison of the completed review with what was planned in the protocol.
Campbell Collaboration: https://onlinelibrary.wiley.com/page/journal/18911803/homepage/submit-a-proposal
The Campbell Collaboration is an international network publishing high quality, transparent and policy-relevant evidence synthesis and maps in the social sectors. These are published in Campbell Systematic Reviews, an open-access journal, which is a member of the Centre for Open Science Registered Reports, thus adheres to peer review and publication of the planned methods as a protocol to minimize bias.
Cochrane is an independent international not-for-profit organization, dedicated to making up-to-date, accurate information about the effects of healthcare readily available worldwide. It produces and disseminates systematic reviews of healthcare interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions.
OSF Registries: https://osf.io/registries
Created by the Center for Open Science, OSF Registries is a scholarly repository built for sharing, searching, and aggregating registrations of research. Using OSF Registries, researchers can create robust, timestamped registrations of research projects, or discover existing registrations on OSF and across connected registries like ClinicalTrials.gov, Research Registry, and more.
PROSPERO is an international database of prospectively registered systematic reviews in health and social care. Key features from the review protocol are recorded and maintained as a permanent record. Systematic reviews should be registered at inception (i.e. at the protocol stage) to help avoid unplanned duplication and to enable comparison of reported review methods with what was planned in the protocol (http://www.prisma-statement.org/Protocols/Registration). The PROSPERO site indicates that "most registrants complete the form in 60 minutes or less," but that is very optimistic. Plan on giving yourself plenty of time to complete the registration.
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 utilize 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.
A full protocol should be ready before registering with PROSPERO.
Submissions must be made before data extraction commences.
Registration forms must be complete.
Submissions must be in English (search strategies and protocols attached to a record may be in any language).
Systematic reviews without an outcome of clear relevance to the health of humans.
Literature reviews that use a systematic search but not a systematic synthesis of the results or outcome.
Systematic reviews assessing sports performance as an outcome.
Methodological reviews that assess ONLY the quality of reporting.
Cochrane protocols are automatically uploaded- To avoid duplication of records, Cochrane protocols should not be registered separately with PROSPERO.