the work of a group developing supplemental domains, measures, or indicators to attach to an existing Core Outcome Set (COS). The group’s role is to identify gaps in the COS, design and validate the add-on content for a specific population, context, or research question, and ensure that these additions enhance relevance without altering the endorsed core outcomes.
Example
The OMERACT Shared Decision-Making Working Group is developing a supplemental module on “decision quality” that can be attached to existing Core Outcome Sets. Their work involves reviewing evidence, consulting with patients and clinicians, and drafting recommendations so that future studies can consistently capture how well shared decision-making is achieved without changing the original COS.