Evaluation of responsiveness of Oswestry low back pain disability index

To assess the response of Oswestry disability index (ODI) among patients undergoing caudal epidural steroid injections for lumbosacral radicular pain. A total number of 107 consecutive patients were analysed. ODI was obtained at preassessment and then at 6 weeks post-injection. At follow-up, patients were asked to rate their condition on an ordinal scale as compared to pre-injection based on their response to five questions (much better, better, same, worse, much worse). As a measure of responsiveness, the effect size and standardized response mean (SRM) was calculated. The mean age of the cohort was 58 years. The mean duration of symptoms was 11 months. The mean Pre-injection ODI for 107 patients was 49(95% CI 46-52). The mean post-injection ODI at 6 weeks was 32(95% CI 28-35). The mean change in ODI was 16.9(95% CI 14-19). The mean change in ODI for much better or much worse group was 21.98(95% CI 18-25). The mean change in ODI for better or worse group was 15(95% CI 10-19) (P = 0.01). The mean change in ODI for same group was -0.6(95% CI -10 to 11). The effect size for the whole group was 1.05. The responsiveness as measured by SRM for the whole group was 0.84. This study shows that ODI can detect small changes in disability over time in patients undergoing caudal epidural injections for lumbosacral radicular pain. It can also differentiate between small and large changes in the level of disability.