Psychometric Properties of the Serbian Version of the Arm, Shoulder, and Hand Disability Self-Assessment Questionnaire: Criterion Validity, Construct Validity, and Internal Consistency

Background/Objectives: The Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire is a widely employed self-report tool for assessing upper extremity function. The aim of this study was to assess the psychometric properties of the Serbian version of the DASH by determining its criterion and construct validity, as well as internal consistency. Methods: This cross-sectional study was conducted among patients with hand and wrist disabilities at the Institute for Orthopedics "Banjica", Serbia. The psychometric properties of the Serbian version of the DASH were analyzed through an examination of its factorial structure and internal consistency. The DASH consists of 30 items, 24 of which assess function, 21 of which focus on physical function and three on social/role function. The remaining six items evaluate symptoms related to pain, tingling/numbness, weakness, and stiffness. Results: A total of 297 patients were included in the study. The mean age was 47.4 +/- 16.8 years, with 50.5% males. Three models were assessed to determine the reliability and validity of the questionnaire across different domains. Model 1 examined a single-factor structure. In Model 2, the items were divided into two domains: Physical Function and Psychosocial/Symptoms. In Model 3, items were subdivided into three domains: Physical Function, Symptoms, and Psychosocial. All models demonstrated an excellent internal consistency with a Cronbach's alpha > 0.9 for most domains. The values for the fit indices Tucker-Lewis index (TLI) and Comparative-Fit Index (CFI) were above their cut-off criteria of 0.9, while the Root Mean Square Error of Approximation (RMSEA) and Standardized Root Mean Square Residual (SRMR) were below the suggested value of 0.06, indicating an excellent level of models fit. Standardized factor loadings were statistically significant (p < 0.05). Conclusions: The present study provided the evidence for the appropriate metric properties of the Serbian version of the DASH. Results support both the unidimensional and multidimensional structures of the DASH.