Core outcome measurement instrument selection for physical function in hand osteoarthritis using the OMERACT Filter 2.1 process.

Objective: Physical function is one of the Outcome Measures in Rheumatology (OMERACT) core outcome domains for hand osteoarthritis studies. Our aim was to select appropriate instrument(s) to measure this domain, as part of the development of a core outcome measurement set.

Methods: Following the OMERACT Filter 2.1 instrument selection process, the (function subscale of) the Australian/Canadian Hand Osteoarthritis Index (AUSCAN), Functional Index for Hand Osteoarthritis (FIHOA) and Michigan Hand Outcomes Questionnaire (MHQ) were assessed for domain match, feasibility, truth and discrimination. Data gathered from available literature, working group and patient surveys, and additional analyses in two hand osteoarthritis cohorts were used to inform a consensus process. Results were summarized in Summary of Measurements Properties tables and reviewed by the OMERACT technical advisory group.

Results: MHQ passed the assessment of domain match and feasibility by the working group and patient research partners. For AUSCAN important limitations in feasibility were noted, but domain match was good. FIHOA did not pass the assessment and was not taken through the follow-up assessment. Based on published literature, reliability and construct/longitudinal validity of both MHQ and AUSCAN fulfilled OMERACT standards. While clinical trial discrimination and thresholds of meaning were good for AUSCAN, results for MHQ were ambiguous.

Conclusion: MHQ was provisionally endorsed as OMERACT core outcome measure for the core domain physical function. While AUSCAN may have better metric properties than MHQ, it received provisional endorsement as a second measure of function due to important feasibility issues. A research agenda to merit full endorsement was set.