The COSMIN Clubs initiative: improving health measurement through collaborative learning.

In this manuscript we describe the development, structure, and contributions of the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) Clubs initiative in strengthening capacity in health measurement research. This descriptive study outlines the rationale, organization, and operation of the COSMIN Clubs, including their international structure, the format of their monthly meetings, and how they engage participants. Insights generated from discussions across multiple Clubs, in addition to an online member feedback survey, were synthesized to highlight key methodological themes and practical learnings. Established in 2023, the COSMIN Clubs currently operate across six regions, four time zones, and four languages, fostering inclusive and multidisciplinary participation. The Clubs provide a platform for discussing ongoing studies and methodological challenges related to measurement properties. Key topics include defining constructs and selecting appropriate study designs. Participants perceived methodological understanding, enhanced research quality, and expanded international collaborations. Discussions have also informed methodological advancements and contributed to ongoing developments in COSMIN guidance. The COSMIN Clubs are a practical extension of the COSMIN initiative that addresses gaps in capacity building, collaboration, and the application of methodological standards. The Clubs promote interactive, international, and multidisciplinary learning to improve the quality of health measurement research and the selection of appropriate outcome measurement instruments in clinical practice and research.