Medicare Advantage Is Associated With Higher Mortality After Antibiotic Spacer Placement for Periprosthetic Joint Infection

Privatized Medicare Advantage (MA) plans are an alternative to traditional Medicare (TM). We sought to identify differences in 90-day postoperative mortality and nonfatal adverse events between TM and MA patients undergoing stage 1 antibiotic spacer placement for periprosthetic joint infection (PJI) of the hip or knee. A nationally representative database was queried from 2015 to 2021 for adult patients undergoing stage 1 antibiotic spacer placement for PJI. Using the International Classification of Disease, 10th Revision, and Current Procedural Terminology codes, as well as hospital charges for antibiotics, patients undergoing stage 1 exchange arthroplasty for PJI were identified. Patients were then grouped into TM and MA cohorts. The primary outcome was the odds of 90-day mortality. Multivariable logistic regressions were conducted to address possible confounding demographic, comorbidity, and hospital characteristics. Of the 40,346 patients undergoing stage 1 spacer placement for PJI, 16,637 (41.2%) had TM coverage and 9,218 (22.8%) had MA coverage. Mortality within 90 days of surgery was higher in the MA cohort (1.4% versus 1.0%, P = 0.004). Multivariable logistic regression demonstrated significantly higher adjusted odds of mortality (adjusted odds ratio = 1.42, 95% confidence interval = 1.11 to 1.81, P = 0.005) in MA patients compared to TM. Even after accounting for available confounders with our multivariable analyses, patients enrolled in an MA plan were more than 40% more likely to die within 90 days of surgery compared to patients who have TM coverage. Further study is necessary to better understand the underlying cause of this finding.