Abstract
The Oswestry Disability Index (ODI) is one of the most widely used questionnaires that assess disability in patients with low back pain (LBP). Responsiveness is both an important psychometric property of an instrument and a key issue for clinicians when choosing suitable outcome measures. The objective of this study was to examine the responsiveness of the Chinese version of the ODI (ODI-Chinese) for subjects with chronic LBP following a physical therapy program. In total, 76 patients with chronic LBP completed the ODI-Chinese, a visual analog scale (VAS) of pain, and the Chinese version of Short Form-36 (SF-36) before and after treatment. All patients also completed a global perception of change Likert scale in condition after the program. The scale was collapsed to produce a dichotomous variable outcome, improved or non-improved. The responsiveness of the instruments was determined using the standardized response means (SRM) and receiver operating characteristics (ROC). After treatment, 56 patients considered themselves to be improved. The SRM of the ODI-Chinese was -1.2 in the improved group and -0.4 in the non-improved group. The area of the ROC curve for the ODI-Chinese was 0.77 (95% CI 0.66-0.89). Therefore, the Chinese version of the ODI is both responsive and appropriate for use in chronic LBP patients after conservative therapy.