Development and validation of the arabic version of the Spine Functional Index (SFI-AR) in patients with spinal disorders

Background The Spine Functional Index (SFI) is a patient-reported outcome measure used to evaluate functional limitations in patients with spinal disorders. However, no validated Arabic version has been available, limiting standardized assessment in Arabic-speaking populations. Methods This prospective cross-sectional validation study translated and culturally adapted the SFI into Arabic (SFI-AR) following internationally accepted guidelines, including forward and back-translation, expert committee review, and pilot testing. Adults aged ≥18 years with spinal pain or dysfunction completed the SFI-AR and the Arabic Chronic Pain Grade Scale (CPGS-AR). A clinically stable subgroup repeated the SFI-AR after 5–10 days. Psychometric evaluation assessed interpretability, internal consistency, test–retest reliability, measurement error, structural validity using exploratory and confirmatory factor analyses, and convergent validity. Results A total of 411 patients were included, with 137 completing the retest. Internal consistency was excellent (Cronbach's α = 0.954), and test–retest reliability was outstanding (ICC(2,1) = 0.998; 95% CI: 0.997–0.998). Measurement error was low (SEM 4.27; MDC 12.56). No significant floor or ceiling effects were observed. Exploratory factor analysis supported an essentially unidimensional structure, explaining 48.29% of the variance, and confirmatory factor analysis showed acceptable fit for a single-factor model (CFI = 0.905; TLI = 0.896; RMSEA = 0.073; SRMR = 0.065). Convergent validity was confirmed by strong correlations with CPGS-AR disability ( ρ = 0.915) and moderate correlations with pain intensity ( ρ = 0.692; p < 0.001). Conclusion The SFI-AR is a reliable, valid, and culturally adapted instrument for assessing spinal function in Arabic-speaking populations, supporting its use in clinical practice and research.