OBJECTIVES : Primary total hip replacement (P_THR) is a common procedure with low complication rates. However, revision THR (R_THR) is associated with significantly greater risks. This study was thus designed to understand risk of infection types (deep vs superficial) and associated costs for patients presenting with either P_THR or R_THR.

METHODS : A retrospective study of patients undergoing P_THR or R_THR between 2014 and 2017 was conducted using IBM® MarketScan® Commercial, Multi-State Medicaid and Medicare Supplemental databases. Patients were categorized by demographic and clinical comorbidities as per the 31 domains of the Elixhauser Comorbidity Index. The outcome were new diagnoses of infection, categorized as deep and superficial within 6 months of surgery. Logistic regression models were evaluated to examine variables associated with infection. Generalized linear regression models were built and adjusted total payments due to infection by category were estimated using least squares means. All payments were adjusted to 2017 consumer price-index.

RESULTS : A total of 92,029 P_THR and 6,298 R_THR patients were included in the analysis. Mean age and percentage female was 62 years (SD: 12.2), 63 years (SD: 12.7) and 54.4%, 56.3% in the P_THR and R_THR cohorts, respectively. Overall 6.1% P_THR and 14.9% R_THR patients presented with any infection (deep infection: 2.7% in P_THR and 11.0% in R_THR). Adjusted total payments in patients with commercial insurance ranged from $100,262 (95% CI: $94,986-$105,831) for superficial to $136,753 (95% CI: $128,486-$145,571) for deep infection in P_THR. For R_THR, payments ranged from $122,373 (95%CI: $97,037-$154,321) to $153,417 (95%CI: 134,586-174,882). Key variables associated with infection included obesity and liver disease for P_THR and; obesity and fluid/electrolyte disorders for R_THR.

CONCLUSIONS : Revision THR patients experience greater risk of infection post-surgery, including risks of deep infections. Ongoing research include understanding patient risk profiles and developing risk mitigation strategies.