STUDY DESIGN: Prospective multicenter longitudinal cohort study.
BACKGROUND: A key component of assessing clinical effectiveness is to compare instruments measuring similar outcomes and to select one that is sufficiently responsive. Despite their widespread use in reporting outcomes, the responsiveness of the Shoulder Pain and Disability Index (SPADI) and the shortened version of the Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH) has not been compared and reported within the same population.
OBJECTIVE: To compare the responsiveness of the SPADI and QuickDASH in a single large cohort of patients.
METHODS: Seven hundred sixty-seven patients referred to physical therapy with shoulder pain completed the SPADI and QuickDASH at baseline, 6 weeks, and 6 months. Patients who improved (improvers) and those who did not improve (nonimprovers) were defined using a 7-point global rating of change scale. Internal and external responsiveness was evaluated.
RESULTS: For improvers, the effect size and standardized response mean were large (greater than 1.00) at 6 weeks for both the SPADI and QuickDASH and further increased for both measures at 6 months. For participants who worsened, negative effect sizes and standardized response means were larger at 6 weeks than at 6 months. The area under the curve was similar for both the SPADI (0.81) and QuickDASH (0.78), increasing to 0.85 for both at 6 months.
CONCLUSION: Both instruments are similarly able to discriminate between clinical improvers and nonimprovers at either follow-up point.
KEY WORDS:clinimetrics, instruments, outcome measures, responsiveness, shoulder