Medicaid or Medicare insurance payer status and household income are associated with outcomes after primary total hip arthroplasty

Our objective was to examine if Medicaid/Medicare health insurance and household income were associated with poorer outcomes after primary total hip arthroplasty (THA). We used multivariable-adjusted Cox regression analyses to assess whether insurance payer type and household income were independently associated with health care utilization outcomes or complications post-THA in a cohort of hospital discharges from the 1998–2014 US National Inpatient Sample, adjusting for demographics, underlying diagnosis for THA, medical comorbidity, and hospital characteristics. In a national cohort of 4,116,485 primary THAs, the mean age was 65.5 years, 57% were female, 87% White, and 83% had osteoarthritis. Compared to private insurance, patients with Medicaid had significantly higher hazard ratio (HR) (95% confidence interval (CI)) for hospital charges above the median, 1.18 (1.15, 1.21); discharge to a rehabilitation/inpatient facility, 1.67 (1.62, 1.72); length of hospital stay > 3 days, 1.62 (1.58, 1.67); and in-hospital post-operative complications including infection, 1.70 (1.47, 1.97); transfusion, 1.13 (1.09, 1.16); revision, 1.55 (1.32, 1.82); and mortality, 1.89 (1.35, 2.63). Results were similar for those with Medicare payer status. Compared to the highest quartile, the lowest income quartile was associated with significantly higher HR (95% CI) of hospital charges above median, 1.43 (1.41, 1.45), and a lower HR of discharge to a rehabilitation/inpatient facility, 0.78 (0.77, 0.79); hospital stay > 3 days, 0.82 (0.80, 0.83); infection, 0.57 (0.50, 0.65); and transfusion, 0.80 (0.79, 0.82). The association of Medicaid/Medicare insurance and income with post-THA health care utilization and complications implies that a better understanding of underlying reasons is needed to improve post-THA outcomes.