Exploratory and Confirmatory Factor Analyses Support the Unidimensionality of the Arabic Quick Disabilities of the Arm, Shoulder and Hand

Abstract

The objective of this investigation was to assess the structural validity of the Arabic Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) in individuals suffering from upper extremity musculoskeletal disorders, utilizing both exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). A group of participants with upper extremity musculoskeletal disorders attending physical therapy clinics were recruited. Upon their initial visit to physical therapy, participants were requested to complete the Arabic versions of the QuickDASH, as well as the Numeric Pain Rating Scale. In order to determine the number of factors, parallel analysis was employed in the EFA, while maximum likelihood was utilized for extraction. The fit of the model identified using EFA was subsequently examined using CFA, incorporating multiple fit indices. The outcomes of the EFA indicated the existence of a one-factor structure, accounting for a considerable 50.22% of the total variance. It was observed that all of the QuickDASH items displayed loadings on the single factor, with values ranging from 0.35 to 0.77. However, the multiple fit indices obtained from the CFA did not provide sufficient support for the fit of the initially proposed unidimensional structure. The data showed good fit to the unidimensional model after adding error covariance: chi-square = 100.52 [degrees of freedom (df) = 40, P < 0.001], chi-square/df = 2.51, Tucker–Lewis index = 0.94, comparative fit index = 0.95, root mean square error of approximation = 0.077 [90% confidence interval (CI) = 0.058-0.096], and standardized root mean residual = 0.048. Ultimately, the findings from the EFA provided evidence supporting the unidimensionality of the Arabic QuickDASH, while the CFA supported the unidimensionality of the QuickDASH after addressing the issue of local dependency between some scale items.