Validity and Reliability of the Activity Card Sort 3 in Persons With Thumb Carpometacarpal Osteoarthritis

Importance Although individuals with thumb carpometacarpal (CMC1) osteoarthritis (OA) commonly experience participation restrictions, participation-focused outcome measures remain underinvestigated, and clinicians primarily rely on assessments of impairments in body structures and functions. Objective To determine the concurrent validity, test–retest reliability, and precision of the Activity Card Sort 3 (ACS3) in individuals with nonoperative CMC1 OA. Design Single-cohort observational psychometric study with repeated measures over a 2-week interval. Setting Remote assessments conducted via videoconferencing. Participants Thirty-three adults with radiographically confirmed CMC1 OA completed two virtual assessments approximately 2 weeks apart. Outcomes and Measures Concurrent validity was examined by comparing ACS3 domain and total scores with the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0). Test–retest reliability of the “current,” “previous,” and “% retained” activities scores was evaluated using intraclass correlation coefficients (ICC 3,1 ). Precision was assessed using the standard error of measurement and minimal detectable change. Results The ACS3 demonstrated good concurrent validity through strong associations with conceptually related WHODAS 2.0 domains. “Current” and “% retained” scores demonstrated good-to-excellent test–retest reliability across all domains. “Current” scores consistently showed the highest reliability and precision. “Previous” scores demonstrated lower reliability and greater measurement error, suggesting recall bias. Carrying forward “previous” scores from session 1 to session 2 improved the reliability of “% retained” scores. Conclusions and Relevance The ACS3 is a valid and reliable measure of participation for individuals with nonoperative CMC1 OA. The “current” and “% retained” scores may support occupational therapy practitioners in conducting participation-focused assessment of persons with CMC1 OA.