Study selection
Inclusion criteria for the study required studies to be relevant to women’s or newborn health (defined as the first 28 days after birth). All stages of COS development were eligible, including registered entries, protocols, systematic reviews or published COS. In the COMET database, studies can be registered either as a COS development process or as a standalone systematic review, exploring outcome reporting across systematic reviews, randomized trials, observational studies, or qualitative studies. These systematic reviews may or may not be part of an overall core outcome study. We included all studies registered as part of a COS or systematic review. Entries from the previous systematic review(11) were identified and progression from their status was explored from protocol to systematic review to core outcome set publication.
Two authors (KG & BD) independently screened all eligible records based on title and summary in the general information section of the COMET database and the title and description on the CROWN database. Any discrepancies were resolved through discussion between authors and retrieval of the full text article if the summary or discussion were unclear. For all studies meeting the inclusion criteria, full text articles were retrieved, where available.