How sharp is the short QuickDASH? A refined content and validity analysis of the short form of the disabilities of the shoulder, arm and hand questionnaire in the strata of symptoms and function and specific joint conditions

To assess and compare content, validity, and specificity of the QuickDASH (Disability of the arm, shoulder and hand questionnaire) as compared to the full-length DASH and other instruments to give a recommendation for its use depending on a specific clinical situation. Data of three large cohorts of patients with shoulder (n = 138), elbow (n = 79), and carpo-metacarpal I (n = 103) arthroplasties were analyzed. The item content of both instruments was compared within the subdomains function and symptoms. Scores and correlations to other instruments were compared in all strata to assess construct convergence. Specificity was quantified and compared using receiver operating characteristics curves (ROC) and effect sizes (in shoulder only). The QuickDASH underestimates symptoms (e.g., 71.1 vs. DASH 66.1 in elbow, 100 = no symptoms, P < 0.001) but overestimates disability (e.g., 72.8 vs. DASH 78.5 in wrist, 100 = full function, P < 0.001). It does not measure the same content as the DASH although the total score levels of both instruments are similar. Furthermore, the QuickDASH is less specific than the DASH in the subdomains, especially in symptoms: for example, area under ROC 0.65 vs. DASH 0.68 in elbow (P = 0.015); effect size in shoulder 1.42 vs. DASH 1.65 (P < 0.001). The short QuickDASH can be recommended for a summary assessment of arm symptoms and function based on the total score in the daily clinical rush. For differentiated assessment of symptoms and function, e.g. for clinical studies, the full-length DASH provides more specific and sophisticated results.