Comparing Medicare Fee-for-Service Beneficiaries with ESKD Who Switched to Medicare Advantage versus Remained in Traditional Medicare.

Patients choosing Medicare Advantage versus Medicare fee-for-service (FFS) differ with respect to race, socioeconomic status, and burden of disease. However, it is unclear whether these differences also occur among patients with kidney failure, who were newly allowed to switch to Medicare Advantage after the 21st Century Cares Act. We used data from the United States Renal Data System to examine differences in characteristics of dialysis patients and kidney transplant recipients who switched from FFS to Medicare Advantage compared with those who stayed with FFS in 2021, the first year such switching was allowed. We used unadjusted and adjusted logistic regression to compare odds of switching among demographic and geographic subgroups. Among 411,513 patients with FFS coverage in 2020, 10.1% switched to Medicare Advantage in 2021. Switchers constituted 12% of the dialysis population and 5% of the kidney transplant population. In the dialysis population, patients of Black race and Hispanic ethnicity were more likely to switch than patients of White race (adjusted odds ratio [OR], 1.69; 95% confidence interval [CI], 1.64 to 1.73 and OR, 1.42; 95% CI, 1.40 to 1.47; respectively), as were patients with dual eligibility for Medicaid (adjusted OR, 1.12; 95% CI, 1.09 to 1.15). Patients living in the South were also more likely to switch to Medicare Advantage than those living in the West (adjusted OR, 1.48; 95% CI, 1.43 to 1.52). Similar differences were observed among kidney transplant recipients. Patients who switched from FFS to Medicare Advantage were disproportionately from historically marginalized groups, including Black, Hispanic, and low-income individuals. They were also more likely to live in the South. These differences may threaten the generalizability of United States Renal Data System data that relies on FFS insurance claims and suggest that comparisons of outcomes between FFS and medicare advantage beneficiaries with kidney failure should be adjusted for key patient characteristics.