In a prospective meta-analysis (PMA), studies are identified and determined to be eligible for inclusion before the results of the studies related to the PMA research question are known PMAs are applicable to high priority research questions where limited previous evidence exists and where new studies are expected to emerge Compared with standard systematic review and meta-analysis protocols, key adaptations should be made to a PMA protocol, including search methods to identify planned and ongoing studies, details of studies that have already been identified for inclusion, core outcomes to be measured by all studies, collaboration management, and publication policy A systematic search for planned and ongoing studies should precede a PMA, including a search of clinical trial registries and medical literature databases, and contacting relevant stakeholders in the specialty PMAs are ideally conducted by a collaboration or consortium, including a central steering and data analysis committee, and representatives from each individual study Usually PMAs collect individual participant data, but PMAs of aggregate data are also possible. PMAs can include interventional or observational studies PMAs can enable harmonised collection of core outcomes, which can be particularly useful for rare but important outcomes, such as adverse side effects Adaptive forms of PRISMA (preferred reporting items for systematic reviews and meta-analyses) and quality assessment approaches such as GRADE (grading of recommendations assessment, development, and evaluation) should be used to report and assess the quality of evidence for a PMA. The development of a standardised set of reporting guidelines and PMA specific evidence rating tools is highly desirable

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