Nature of patient participation where detail is reported (n = 27).

The methods used to develop COS (n = 307).

The scope of included studies (n = 307).

Participant groups involved in selecting outcomes for inclusion in COS (n = 307).

BackgroundThe Core Outcome Measures in Effectiveness Trials (COMET) database is a publically available, searchable repository of published and ongoing core outcome set (COS)...

Reasons for exclusion at full text stage.