Medicare Advantage Enrollment and Disenrollment Among Persons With Alzheimer Disease and Related Dementias.

Importance: Large enrollment growth has been observed in the Medicare Advantage program, but less is known about enrollment patterns among persons with Alzheimer disease and related dementias (ADRD). Objective: To evaluate patterns in Medicare Advantage enrollment and disenrollment among beneficiaries with or without ADRD. Design, Setting, and Participants: This cross-sectional study used 6 national data sources between January 1, 2011, and December 31, 2018. Analyses were performed between June 2021 and August 2022. The cohort comprised US Medicare beneficiaries with acute or postacute care utilization between 2013 and 2018. Exposure: ADRD diagnosis from an acute or postacute care encounter Medicare data source. Main Outcomes and Measures: Enrollment in Medicare Advantage, disenrollment from Medicare Advantage to traditional Medicare, and contract exit (leaving a Medicare Advantage contract for traditional Medicare or a different Medicare Advantage contract). Results: The 32 796 872 Medicare beneficiaries in the cohort had a mean (SD) age of 74.0 (12.5) years and included 18 228 513 females (55.6%). Enrollment in Medicare Advantage among beneficiaries with ADRD increased from 24.7% (95% CI, 24.7%-24.8%) in 2013 to 33.0% (95% CI, 32.9%-33.1%) in 2018, an absolute increase of 8.3 percentage points and a 33.4% relative increase after adjusting for demographic characteristics, comorbid conditions, and utilization and including county fixed effects. Among beneficiaries without ADRD, enrollment in Medicare Advantage increased by 8.2 percentage points from 27.6% (95% CI, 27.6%-27.6%) in 2013 to 35.8% (95% CI, 35.8%-35.8%) in 2018, a 29.7% relative increase over the study period. Beneficiaries with ADRD were 1.4 times as likely to disenroll from their Medicare Advantage contract to traditional Medicare (4.4% vs 3.2% in 2017-2018; P < .001) in adjusted analyses. Regardless of ADRD status, beneficiaries had similar rates of switching to a new Medicare Advantage contract. Differences in contract exit rates were associated with higher rates of disenrollment from Medicare Advantage to traditional Medicare among beneficiaries with ADRD vs those without ADRD (16.3% [95% CI, 16.2%-16.3%] vs 15.1% [95% CI, 15.1%-15.1%]). Beneficiaries with ADRD and dual eligibility for Medicaid enrollment had higher rates of contract exit than those without dual eligibility (19.7% [95% CI, 19.6%-19.7%] vs 14.9% [95% CI, 14.8%-14.9%]), and these differences were even greater than those among beneficiaries without ADRD and with and without dual-eligibility status, respectively (18.3% [95% CI, 18.2%-18.3%] vs 13.8% [95% CI, 13.7%-13.8%]). Conclusions and Relevance: In this cross-sectional study of the Medicare population with acute and postacute care use, beneficiaries with ADRD had increasing enrollment in the Medicare Advantage program, proportional to the growth in overall enrollment, but their disenrollment from Medicare Advantage in the following year remained higher compared with beneficiaries without ADRD. The findings highlight the need to understand the factors associated with higher disenrollment rates and determine whether such rates reflect access or quality challenges for beneficiaries with ADRD.