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

Background: 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.

Methods: 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.

Results: 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.

Conclusions: 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.