A protocol for the development of a core outcome set for adults with depression

Background and Objective Heterogeneous outcome measurement limits the comparison and combination of results from randomized controlled trials and observational studies aimed at evaluating therapeutic interventions for depression. We report here the protocol for the development of a Core Outcome Set (COS) for adults with depression. Methods Development will follow a multistep approach with: (1) generating outcome domains that matter to people with lived experiences of depression, health care professionals, and carers through a large online international survey using open-ended questions; (2). selecting domains based on the preferences of key interest holders through an international online preference elicitation survey; and (3) identifying relevant outcome measures with measurement properties considered sufficient through several systematic reviews conducted according to COnsensus-based Standards for the selection of health Measurement INstruments standards. Discussion The protocol describes a proof-of-concept approach to include large numbers of individuals from all key interest holder groups in COS development, which could be replicated in other conditions and contexts.