Abstract
BACKGROUND: The Quick Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH) and the Patient-Specific Functional Scale (PSFS) are commonly used outcome instruments for measuring self-reported disability in patients with shoulder pain. To date, few studies have evaluated the responsiveness and estimated their minimal important change (MIC). Further assessment will expand the current knowledge and improve the interpretability of these instruments in clinical and research practice. The purpose of this prospective cohort study with 3 months follow-up was to evaluate the responsiveness of the QuickDASH and PSFS in patients with shoulder pain, and to estimate their MICs by using two different anchor-based methods. METHODS: Patients with shoulder pain recruited at a multidisciplinary hospital outpatient clinic completed the QuickDASH and PSFS at baseline and at 3 months follow-up. The responsiveness was evaluated by using a criterion approach with the area under the receiver operating characteristic curve (AUC) and a construct approach by testing 9 a-priori hypotheses. The MIC was assessed using two anchor-based MIC methods. RESULTS: 134 patients participated at baseline and 117 (87.3%) at 3 months follow-up. The AUC was acceptable for both QuickDASH (0.75) and PSFS (0.75). QuickDASH met 7 (77.8%) and PSFS 8 (88.9%) of the hypotheses. None of the instruments showed signs of floor and ceiling effects. The MIC estimates ranged from 10.8 to 13.6 for QuickDASH and from 1.9 to 2.0 for PSFS, depending on the method used. CONCLUSION: This study demonstrates that both the QuickDASH and PSFS are responsive measures of disability in patients with shoulder pain. The estimated MIC values were presented.