To establish the validity of three self-report scales used to measure function following arthroplasty for osteoarthritis (OA) of the carpometacarpal joint.
Persons with OA of the carpometacarpal joint (n=122) were assessed on one occasion 9-117 months following tendon interposition arthroplasty. They completed three self-report measures of hand/upper limb disability: the Australian/Canadian Osteoarthritis Hand Index (AUSCAN), the Patient-Rated Wrist Hand Evaluation (PRWHE), and the Disabilities of Arm, Shoulder and Hand (DASH). They also completed the Short Form 36 (SF-36) and performed tests of strength, range of motion (ROM), and dexterity. Factor analysis and correlations were used to determine the association among the scales and subscales considered to measure similar constructs (e.g., pain and physical disability). Correlations between the scales and measures of impairment were also conducted to examine construct validity of the disability measures. t-Tests evaluated the hypotheses that subjects with isolated hand OA would have lower scores than those with additional joint involvement.
All three scales or their subscales loaded on one factor. Convergent validity of the disability measures was demonstrated by high correlations between similar subscales (r>0.75), and divergent validity by a lack of correlation between the measures and self-report hand appearance. As expected, correlations between disability and strength, dexterity, or a global measure of ROM were higher than with ROM of individual joints. The AUSCAN and the DASH were better able to discriminate those with localized hand OA from those with involvement of other joints.
The AUSCAN, PRWHE, and DASH are valid assessments of pain and/or disability of hand OA, and provide information distinct from impairment measures.