Do not register too early. Your systematic review protocol should be complete before you submit your registration request.
Registering reviews that are never done is unhelpful to the research community and may discredit the research team.
You should therefore have the necessary resource in place to complete the review before you register your protocol (notification of award of research funding or firm commitment that author time is available for unfunded projects).
PROSPERO relies on the integrity of researchers for the accuracy of the data supplied, and the named contacts are accountable for the content of their records. We routinely monitor the time frame given in submissions and seek clarification where this appears overly ambitious prior to confirming registration and providing a PROSPERO registration number. Amendments and updates to the record are made transparent in the audit trail within each record.
On rare occasions, peer reviewers and editors using PROSPERO to compare what was planned with what is reported in the final manuscript, have identified that the initial registration date in PROSPERO post-dates the manuscript submission date to the journal. In these cases the logical explanation is that the stage of review was inaccurately completed in the PROSPERO registration form; otherwise the submission would have been rejected. In such cases, the named contact will be alerted to the issue and given the opportunity to respond within two weeks. If it is confirmed that incorrect information was provided, or no response is received, the content of the PROSPERO record will be removed, leaving the title and the details of the named contact and the following statement:
Since publication of this record it has been established that information provided initially about the stage of the review and anticipated completion date was inaccurate. The review had actually progressed beyond the stage of eligibility for PROSPERO.
Prospective registration aims to facilitate the comparison of reported review findings with what was planned a priori in the protocol. Reviews should ideally be registered before screening against eligibility criteria commences. However, reviews are currently accepted provided they have not progressed beyond the completion of data extraction.
Protocol details for this review should be sought from the named contact.