The 30-item disabilities of the arm, shoulder and hand (DASH) questionnaire is increasingly used in clinical research involving upper extremity musculoskeletal disorders. From the original DASH a shorter version, the 11-item QuickDASH, has been developed. Little is known about the discriminant ability of score changes for the QuickDASH compared to the DASH. The aim of this study was to assess the performance of the QuickDASH and its cross-sectional and longitudinal validity and reliability.
The study was based on extracting QuickDASH item responses from the responses to the full-length DASH questionnaire completed by 105 patients with a variety of upper extremity disorders before surgery and at follow-up 6 to 21 months after surgery. The DASH and QuickDASH scores were compared for the whole population and for different diagnostic groups. For longitudinal construct validity the effect size and standardized response mean were calculated. Analyses with ROC curves were performed to compare the ability of the DASH and QuickDASH to discriminate among patients classified according to the magnitude of self-rated improvement. Cross-sectional and test-retest reliability was assessed.
The mean DASH score was 34 (SD 22) and the mean QuickDASH score was 39 (SD 24) at baseline. For the different diagnostic groups the mean and median QuickDASH scores were higher than the corresponding DASH scores. For the whole population, the mean difference between the QuickDASH and DASH baseline scores was 4.2 (95% CI 3.2–5.3), follow-up scores was 2.6 (1.7–3.4), and change scores was 1.7 (0.6–2.8).
The overall effect size and standardized response mean measured with the DASH and the QuickDASH were similar. In the ROC analysis of change scores among patients who rated their arm status as somewhat or much better and those who rated it as unchanged the difference in the area under the ROC curve for the DASH and QuickDASH was 0.01 (95% CI -0.05–0.07) indicating similar discriminant ability.
Cross-sectional and test-retest reliability of the DASH and QuickDASH were similar.