Minimal clinically important differences in health-related quality of life after total hip or knee replacement

Objectives We aimed first to summarise minimal clinically important differences (MCIDs) after total hip (THR) or knee replacement (TKR) in health-related quality of life (HRQoL), measured using the Short-Form 36 (SF-36). Secondly, we aimed to improve the precision of MCID estimates by means of meta-Analysis. Methods We conducted a systematic review of English and non-English articles using MEDLINE, the Cochrane Controlled Trials Register (1960-2011), EMBASE (1991-2011), Web of Science, Academic Search Premier and Science Direct. Bibliographies of included studies were searched in order to find additional studies. Search terms included MCID or minimal clinically important change, THR or TKR and Short-Form 36. We included longitudinal studies that estimated MCID of SF-36 after THR or TKR. Results Three studies met our inclusion criteria, describing a distinct study population: primary THR, primary TKR and revision THR. No synthesis of study results can be given. Conclusions Although we found MCIDs in HRQoL after THR or TKR have limited precision and are not validated using external criteria, these are still the best known estimates of MCIDs in HRQoL after THR and TKR to date. We therefore advise these MCIDs to be used as absolute thresholds, but with caution.