Responsiveness of the shoulder function assessment scale in patients with rheumatoid arthritis.

OBJECTIVES: To investigate the responsiveness of the Shoulder Function Assessment scale (SFA) in patients with rheumatoid arthritis (RA). METHODS: In 35 patients with RA receiving a (peri-)articular injection because of local shoulder complaints the SFA, impact of shoulder function on activities of daily living, active shoulder range of motion (ROM), the 28 joint count Disease Activity Score (DAS28), and the Health Assessment Questionnaire (HAQ) were measured before and 4-6 weeks after treatment. Responsiveness was determined using the standardised response mean (SRM), effect size (ES), and responsiveness ratio (RR). RESULTS: Overall, significant improvement was seen according to the SFA (mean change 10.9 (95% confidence interval 6.5 to 15.3)), active shoulder ROM (except external rotation), and the impact of shoulder function on daily activities. In addition, the DAS28 and HAQ scores improved significantly. The responsiveness of the SFA was excellent, with the SRM, ES, and RR being -0.86, -1.16, and 1.28, respectively. CONCLUSIONS: In addition to its good validity and reliability, the SFA proved to have a high sensitivity to clinical changes in patients with RA who received local treatment for shoulder complaints.