A Scoping Review of Published and Ongoing Prospective Meta-Analyses in Health Research: Study Protocol

Background Prospective meta-analysis (PMA) is an emerging evidence synthesis methodology, in which the study selection criteria, hypotheses and analyses are finalised prior to the knowledge of included study results. This has numerous benefits over retrospective meta-analysis, including a reduction in selection bias, selective outcome reporting and publication bias and improved data harmonisation. Yet, common misunderstandings of the PMA methodology remain, leading to inappropriate and/or suboptimal implementation by researchers. Objectives To investigate the landscape of the published and ongoing prospective meta-analyses. Methods We will systematically search the International prospective Register of Systematic Reviews (PROSPERO) for PMAs from inception to January 2023 and screen these studies in COVIDENCE. The results of this search will be combined with a search of medical databases (PubMed, Embase, Cochrane Database of Systematic Reviews) up to 2018, to capture PMA that started prior to the launch and subsequently increasingly wide implementation of PROSPERO in February 2011. All PMAs conducted in human health research will be eligible for inclusion. All records will be doublescreened, and data will be double extracted, with conflicts resolved through consensus. Dissemination Insights from this scoping review will inform adaptions to current PMA guidelines and thus assist researchers in planning future PMAs in their fields. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Dr Lene Sediler is supported by an Emerging Leadership 1 NHMRC Fellowship (APP2009432) ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: N/A I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes N/A - protocol only