Validity of the QuickDASH in Patients With Shoulder-Related Disorders Undergoing Surgery
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STUDY DESIGN: Validity study. OBJECTIVE: To determine the validity of the shortened version of the Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH) in comparison to the full DASH in patients undergoing total shoulder arthroplasty (TSA) and rotator cuff repair (RCR). BACKGROUND: The QuickDASH is a shorter version of the DASH that may reduce respondent burden while retaining similar measurement properties. METHODS: One hundred thirty-two patients undergoing TSA or RCR were assessed at baseline and at 3 and 6 months postoperatively. The patients completed the DASH, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form self-report section, and the Western Ontario Rotator Cuff index, and were tested to determine their shoulder range of motion and isometric strength. The differences between scores on the DASH and QuickDASH across the scale range were evaluated using the Bland-Altman technique. Item difficulty, correlations with other patient-reported outcome measures, and physical impairments were used to assess validity. Known group validity was assessed by examining differentiation of work status. Responsiveness was assessed through standardized response means. RESULTS: QuickDASH scores were slightly higher than DASH scores, with a mean difference of 1 to 1.3 points for the TSA group and 1 to 3 points for the RCR group tested preoperatively, and at 3 months and 6 months postoperatively, although limits of agreement were wide (ranging from -10 to 13 across all estimates). The QuickDASH items were distributed across the full DASH, when ranked by item difficulty, for both patient groups. The correlation between the QuickDASH and DASH was almost perfect (r>0.92). Correlations between the DASH/QuickDASH and other patient-reported outcome measures ranged from moderate to very large (American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form self-report section, r=0.47-0.85; Western Ontario Rotator Cuff index, r=0.83-0.91), whereas correlations to impairments were small to moderate. Correlation estimates varied by less than 0.07, depending on whether the DASH or QuickDASH was used, suggesting equivalent construct validity. Both the DASH and QuickDASH discriminated between working and nonworking patients, with similar group differences and statistical significance (P<.01). The QuickDASH and DASH showed similar responsiveness between presurgery and 6-month follow-up (standardized response mean, 1.1 following TSA and 0.8 following RCR). CONCLUSION: When substituting the QuickDASH for the full DASH, similar score estimates, discrimination of clinically relevant subgroups, and responsiveness can be expected across patients following TSA and RCR.
