Total Hip Arthroplasty versus Education and Exercise: A Secondary Analysis of Propensity Matched Data Comparing Outcomes Across Hip Osteoarthritis Symptom Severity.

Background: Using propensity-matched data, we have previously shown that total hip arthroplasty (THA) provides superior outcomes to an education and exercise (Edu + Ex) program in patients who have hip osteoarthritis (OA), overall. This study investigated whether treatment effects of Edu + Ex versus THA differ across patients who have varying degrees of hip OA symptom severity.

Methods: This was a secondary analysis of propensity-matched patients who had hip OA who underwent THA or an Edu + Ex program (1:1 match ratio). In this analysis, matched patients were divided into three strata based on their propensity score (low severity: < 0.33; moderate severity: ≥ 0.33 and < 0.67; and high severity: ≥ 0.67). The propensity score reflected symptom severity, and a greater score indicated more severe symptoms. Between-group treatment effects (pain, function, and quality of life) were estimated as the mean difference (MD) in change from pretreatment to three and 12 months postintervention using linear mixed models within each severity stratum.

Results: Patients (n = 266) were classified into three strata: low symptom severity (n = 55), moderate symptom severity (n = 115), and high symptom severity (n = 96). Treatment effects at 12 months revealed statistically significant differences in favor of THA over Edu + Ex across all three severity strata for pain (low: MD 26.3, 95% confidence interval [CI] 18.6 to 33.9; moderate: MD 35.6, 95% CI 30.0 to 41.2; high: MD 40.0, 95% CI 32.5 to 47.4) and for function and quality of life. All estimated treatment effects were clinically relevant.

Conclusions: From this analysis of well-matched observational data, we identified a clinically relevant effect in favor of THA over Edu + Ex across all outcomes, regardless of hip OA symptom severity. These findings question whether THA should be prioritized only for those patients who have severe hip OA symptoms, but require confirmation in a trial.