Shoulder disability questionnaire design and responsiveness of a functional status measure

The Shoulder Disability Questionnaire (SDQ) is a measure covering 16 items designed to evaluate functional status limitation in patients with shoulder disorders. The responsiveness of the SDQ was evaluated for 180 patients with soft tissue shoulder disorders, without underlying systemic disorders. These patients participated in a randomized placebo-controlled trial, in which ultrasound and electrotherapy appeared to be ineffective as adjuvants to standardized exercise therapy. At baseline and at 6-week follow-up, patients completed the SDQ and rated severity of shoulder pain and their chief complaint, while a research physiotherapist rated severity of symptoms and restriction of mobility. At the 6-week follow-up, patients also rated overall change since baseline. According to the calibrated responsiveness ratio (CRR) and the area under the receiver-operator characteristic curve (AUC) the SDQ discriminates accurately between self-rated clinically stable and improved subjects. The presented results suggest that the SDQ is as responsive as the compared outcome measures, and therefore is ready for use in clinical trials.