Validity and responsiveness of the short version of the western Ontario rotator cuff index (Short-WORC) in patients with rotator cuff repair

©2018 Journal of Orthopaedic & Sports Physical Therapy® U STUDY DESIGN: Clinical measurement. U BACKGROUND: Recently, the Western Ontario Rotator Cuff Index (WORC) was shortened, but few studies have reported its measurement properties. U OBJECTIVE: To compare the validity and responsiveness of the short version of the Western Ontario Rotator Cuff Index (Short-WORC) and the WORC (disease-specific measures) with those of the Shoulder Pain and Disability Index (SPADI) and the simple shoulder test (SST) (joint-specific measures); the Disabilities of the Arm, Shoulder and Hand (DASH) (a region-specific measure); and the Medical Outcomes Study 12-Item Short-Form Health Survey version 2 (SF-12v2) (a general health status measure) in patients undergoing rotator cuff repair (RCR). U METHODS: A cohort of patients (n = 223) completed the WORC, SPADI, SST, DASH, and SF-12v2 preoperatively and at 3 and 6 months after RCR. Short-WORC scores were extracted from the WORC questionnaire. The construct validity (Pearson correlations) and internal responsiveness (effect size [ES], standardized response mean [SRM], relative efficiency [RE]) of the Short-WORC were calculated. U RESULTS: The Short-WORC was strongly correlated with the WORC (r = 0.89-0.96) and moderately to strongly correlated with non-disease-specific measures at preoperative and postoperative assessments (r = 0.51-0.92). The Short-WORC and WORC were equally responsive (REShort-WORC/WORC = 1) at 0 to 6 months and highly responsive overall at 0 to 3 months (ESShort-WORC, 0.72; ESWORC, 0.92; SRMShort-WORC, 0.75; SRMWORC, 0.81) and 0 to 6 months (ESShort-WORC, 1.05; ESWORC, 1.12; SRMShort-WORC, 0.89; SRMWORC, 0.89). The responsiveness of the comparator measures (SPADI, SST, DASH, SF-12v2) was poor to moderate at 0 to 3 months (ES, 0.07-0.55; SRM, 0.09-0.49) and 0 to 6 months (ES, 0.05-0.78; SRM, 0.07-0.78). U CONCLUSION: The Short-WORC and WORC have similar responsiveness in patients undergoing RCR, and are more responsive than non-disease-specific measures. Future studies should focus on validation of the Short-WORC in samples representing the spectrum of rotator cuff disorders. J Orthop Sports Phys Ther 2018;48(5):409-418