Purpose: The Oswestry Disability Index (ODI) is one of the most common patient-reported outcome measures used for low back pain (LBP). Since it was not available in Indonesian, this study aimed to perform a cross-cultural adaptation of ODI to Indonesian and evaluate its psychometric properties.
Methods: We performed a cross-cultural adaptation of ODI v2.1a into Indonesian language (ODI-ID) and determined its internal consistency, test-retest reliability, measurement error, confirmatory factor analysis, floor-ceiling effect, and construct validity by hypotheses testing of its correlation with Short Form-36 (SF-36) and visual analog scale (VAS). Adults (> 17 years of age) diagnosed with low back pain were included.
Results: A total of 96 subjects were included in this study. The original ODI questionnaire was translated into an Indonesian version and showed a good internal consistency (Cronbach's alpha = 0.90) and good reliability (intraclass correlation = 0.97). The standard error of measurement values of 3.35 resulted in a minimal detectable change score of 9. Nine out of nine (100%) a priori hypotheses were met, confirming the construct validity. A strong correlation was found with the physical component of SF-36 (0.77 and 0.76 for pain and physical function, respectively) and VAS (0.79). Confirmatory factor analysis resulted in a poor but significant fit to the original one-factor structure and the static-dynamic two-factor structure. Floor-ceiling effects were not found.
Conclusions: The Indonesian version of ODI displayed similar reliability, validity, and psychometric characteristics to the original ODI. This questionnaire will be a suitable instrument for assessing LBP-related disability for Indonesian-speaking patients.
Keywords: Cross-cultural adaptation; Indonesian; Low back pain; Oswestry Disability Index.