Measurement properties of the DASH questionnaire across upper extremity disorders: A COSMIN systematic review.

BACKGROUND: The Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire is one of the most widely used patient-reported outcome measures (PROMs) in upper extremity rehabilitation. Previous reviews have focused on specific diagnoses or shortened versions, with methodological limitations. PURPOSE: To comprehensively evaluate the measurement properties of the DASH questionnaire across upper extremity conditions using COSMIN guidelines. STUDY DESIGN: Systematic review of measurement properties. METHODS: Following COSMIN guidelines, we systematically evaluated content validity, structural validity, internal consistency, cross-cultural validity, measurement invariance, reliability, measurement error, criterion validity, construct validity, and responsiveness. Risk of bias was assessed, and the quality of evidence was graded. The review protocol was prospectively registered in PROSPERO (CRD42024599669). RESULTS: A total of 146 studies were included. Five diagnostic categories with sufficient evidence were analyzed separately: upper extremity disorders, shoulder disorders, carpal tunnel syndrome, rheumatoid arthritis, and distal radius fractures. Content validity demonstrated moderate-to-high evidence across most populations. Structural validity findings were heterogeneous, with many studies lacking adequate factor analysis or sample size justification. Internal consistency and reliability showed strong evidence across disorders. Cross-cultural validity and measurement invariance were insufficiently evaluated, particularly outside the original language context. Evidence for construct validity and responsiveness was generally moderate but limited in some populations. CONCLUSION: The DASH demonstrates overall strong reliability and acceptable validity across upper extremity conditions, though structural and cross-cultural validity require further investigation. These findings provide guidance for hand therapy clinicians and researchers regarding appropriate interpretation and application of the DASH in clinical practice and research.