Comparison of mortality between Medicare Advantage and traditional Medicare beneficiaries with kidney failure

To compare risk-adjusted 1-year mortality between Medicare Advantage (MA) and traditional Medicare (TM) enrollees with kidney failure who initiated dialysis.

Longitudinal analysis of mortality and enrollment data for Medicare beneficiaries.

The study compared mortality between MA and TM enrollees with kidney failure who initiated dialysis in 2016, accounting for their enrollment switches between MA and TM during 12 months prior to dialysis initiation. Analyses were adjusted for risk scores and fixed effects for the month of dialysis initiation and county of residence.

The difference in risk-adjusted 1-year mortality between MA stayers (Medicare beneficiaries who were continuously enrolled in MA prior to dialysis initiation) and TM stayers (those who were continuously enrolled in TM prior to initiating dialysis) was -0.1 percentage points (95% CI, -1.0 to 0.8); however, the difference increased to -1.0 percentage points (95% CI, -3.2 to 1.2) when comparing TM-to-MA switchers (those who switched from TM to MA before initiation) with TM stayers, a comparison more prone to favorable selection bias given our finding that TM-to-MA switchers were healthier than MA stayers.

Among Medicare beneficiaries with kidney failure who initiated dialysis, risk-adjusted 1-year mortality rate is not different between MA and TM stayers. If there is remaining favorable selection in MA due to unobserved health status, our finding provides a lower-bound estimate of the MA impact on mortality among beneficiaries with kidney failure.