Psychometric evaluation supported construct validity, temporal stability, and responsiveness of the Osteoarthritis...

The Osteoarthritis Questionnaire (OA-Quest) is a new measure of individual burden of osteoarthritis, composing seven brief (4-11 items; total 42 items), independent scales. This study describes the psychometric evaluation of the OA-Quest. Specifically, temporal stability, convergent and discriminant validity, and responsiveness of the OA-Quest to joint replacement surgery were examined.

Participants were drawn from rheumatology (n = 62), orthopedic (n = 90), and community (n = 175) settings. Temporal stability of the OA-Quest was evaluated over a 2-week period and was assessed with intraclass correlation coefficients. Responsiveness was assessed with standardized effect sizes and paired samples t-tests. Convergent and discriminant validity was assessed with a multitrait multimethod confirmatory factor analysis (MTMM CFA).

The OA-Quest scales had high temporal stability, with intraclass correlation coefficients between 0.75 (lost productivity) and 0.94 (physical limitations) and showed improvements of expected magnitude and direction 3 months after joint replacement surgery, supporting their responsiveness. MTMM CFA supported the convergent and discriminant validity of the OA-Quest, demonstrated by adequate model fit (χ² = 483.54, df = 184, P < 0.001, comparative fit index = 0.95, Tucker-Lewis index = 0.93, root mean square error of approximation = 0.07, standardized root mean square residual = 0.06) and factor loadings of the expected magnitude and direction.

The OA-Quest has strong evidence of temporal stability, construct validity, and is responsive to change following joint replacement surgery.