Structural Validity of the Arabic Roland-Morris Disability Questionnaire Using Confirmatory Factor Analysis in...

Background/Objective: Low back pain (LBP) is a leading cause of disability worldwide, and patient-reported outcome measures such as the Roland-Morris Disability Questionnaire (RMDQ) are essential for assessing LBP-related disability. While the Modern Standard Arabic version of the RMDQ has demonstrated preliminary reliability, its structural validity has not been thoroughly evaluated. This study aimed to assess the structural validity of the Modern Standard Arabic RMDQ using confirmatory factor analysis (CFA). Methods: A cross-sectional study was conducted for 113 patients with LBP recruited from outpatient physical therapy clinics in Saudi Arabia. Participants completed the Modern Standard Arabic RMDQ, a 24-item instrument scored dichotomously. CFA was performed using the Weighted Least Squares Mean and Variance adjusted estimator to test a unidimensional model. Model fit was assessed using Root Mean Square Error of Approximation (RMSEA), Standardized Root Mean Square Residual (SRMR), Tucker-Lewis Index (TLI), and Comparative Fit Index (CFI). Reliability was evaluated using McDonald's omega (ω). Results: The initial one-factor CFA model showed close to acceptable fit (RMSEA = 0.044; SRMR = 0.149; TLI = 0.94; CFI = 0.93). After accounting for significant residual correlations between item pairs (items 4 & 21; 13 & 18), model fit improved (Δχ² = 22.33; Δdf = 2; p < 0.001) (RMSEA = 0.038; SRMR = 0.145; TLI = 0.95; CFI = 0.95). Most items had significant loadings on the latent construct, except item 2. McDonald's ω was 0.91, indicating excellent internal consistency. Conclusions: The findings of this study provide supportive evidence for the structural validity and internal consistency of the Modern Standard Arabic version of the RMDQ and suggest the presence of a dominant unidimensional structure. The Arabic RMDQ may be useful for assessing LBP-related disability in Arabic-speaking patients with LBP, although further validation studies are warranted.