Examination of the factor structure of the Disabilities of the Arm, Shoulder, and Hand questionnaire.

OBJECTIVE The Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire is a global scale evaluating the impact of upper-extremity disorders. We sought to validate or challenge the unidimensional factor structure of the DASH. METHOD Secondary analysis was performed on data collected from outpatient clinics. Factor analysis was performed in two steps, exploratory factor analysis (EFA) followed by confirmatory factor analysis (CFA). To provide further support for unidimensionality, fit statistics were calculated using the Andrich Rasch rating-scale model. RESULTS EFA revealed three potential factors (eigenvalues = 18.40, 1.56, and 1.54). CFA was performed fitting a three-factor model. Tucker-Lewis Index (.99) and standardized root mean square residual (.05) values indicated good fit. Comparative fit index (.89) and root mean square error of approximation (.13) did not. When divided into three constructs, only one item misfit. CONCLUSION More research is needed to determine situations in which division of the DASH may enhance interpretability.