Responsiveness and minimal important differences after revision total hip arthroplasty

Background. The health-related quality of life (HRQoL) is currently weighted more heavily when evaluating health status, particularly regarding medical treatments and interventions. However, it is rarely used by physicians to compare responsiveness. Additionally, responsiveness estimates derived by the Harris Hip Score (HHS) and the Short Form 36 (SF-36) before and after revision total hip arthroplasty (THA) have not been clinically compared. This study compared responsiveness and minimal important differences (MID) between HHS and SF-36. Methods. All revision THA patients completed the disease-specific HHS and the generic SF-36 before and 6 months after surgery. Scores using these instruments were interpreted by generalized estimating equation (GEE) before and after revision THA. The bootstrap estimation and modified Jacknife test were used to derive 95% confidence intervals for differences in the responsiveness estimates. Results. Comparisons of effect size (ES), standardized response means (SRM), relative efficiency (RE) (>1) and MID indicated that the responsiveness of HHS was superior to that of SF-36. The ES and SRM for pain and physical functions in the HHS were significantly larger than those of the SF-36 (p < 0.001). Conclusion. The data in this study indicated that clinicians and health researchers should weight disease-specific measures more heavily than generic measures when evaluating treatment outcomes.