Measurement properties of the German Michigan Hand Outcomes Questionnaire in patients with trapeziometacarpal osteoarthritis.
OBJECTIVE
To investigate the reliability, validity, and responsiveness of the Michigan Hand Outcomes Questionnaire (MHQ) in patients with trapeziometacarpal (TMC) joint osteoarthritis (OA).


METHODS
In this prospective observational study, patients diagnosed with TMC joint OA who received either conservative or surgical treatment were included. At baseline and at 1 year following the beginning of treatment, we measured key pinch strength and the patients filled out the MHQ, the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, and the Short Form 12 health survey. Patients also completed these questionnaires 2-11 days after the last study visit. In order to analyze the measurement properties of the MHQ, we calculated test-retest reliability (intraclass correlation coefficient [ICC]), internal consistency (Cronbach's alpha for the 6 subscales), construct validity (Pearson's correlation coefficient [r]), responsiveness (effect sizes), and the minimum important change (MIC).


RESULTS
We included 177 patients, of whom 109 were scheduled for surgery. The mean ± SD MHQ total score for surgical patients increased from 48 ± 14 at baseline to 75 ± 18 at 1 year (P ≤ 0.001). In contrast, no treatment effect was observed in the conservative group (P = 0.74). The MHQ total score showed excellent test-retest reliability (ICC 0.95) and correlated strongly with the DASH (r = -0.77). Internal consistency of the MHQ subscales ranged between 0.77 and 0.89. A large effect size of 1.7 was found for the surgical patients, with an MIC of 17 points.


CONCLUSION
The MHQ demonstrated good reliability, validity, and responsiveness in patients with TMC joint OA and can be recommended as a suitable assessment instrument in this population.