The influence of socioeconomic status on utilization and outcomes of elective total hip replacement: a multicity population-based longitudinal study.

OBJECTIVE In countries with universal health coverage, socioeconomic status is not expected to influence access to effective treatment and its prognosis. We tested whether socioeconomic status affects the rates of elective total hip replacement and whether it plays a role in early and late outcomes. DESIGN Multicity population-based longitudinal study. SETTING AND PARTICIPANTS From Hospital Registries of four Italian cities (Rome, Milan, Turin, and Bologna), we identified 6140 residents aged 65+ years undergoing elective total hip replacement in 1997-2000. MAIN OUTCOME MEASURES An area-based (census block) income index was used for each individual. Poisson regression yielded rate ratios (RR) of population occurrence by income level. Logistic regression estimated odds ratios (OR) of selected outcomes within 90 days. Cox proportional hazard models evaluated effects of income on rates of revision of total hip replacement and mortality up to 31 December 2004. Analyses were adjusted for age, gender, city of residence, and coexisting medical conditions. RESULTS Low-income people were less likely than high-income counterparts to undergo total hip replacement [RR = 0.87, 95% confidence interval (CI) 0.81-0.95]; the effect was stronger among those aged 75+ years (RR = 0.76, 95% CI = 0.66-0.86). Low income was associated with higher risk of acute adverse medical events (P trend = 0.05) and of general infections and decubitus ulcer (P trend = 0.02) within 90 days. The effects were even higher among those aged 75+ years. No effects were found either for orthopaedic complications within 90 days or for revision and mortality. CONCLUSIONS Total hip replacement is underutilized among elderly deprived individuals. Disadvantaged patients seem more vulnerable to acute adverse medical events after surgery. The evidence of unmet need and poor prognosis of low social class people has important implications for health care policy.