IMPORTANCE: Alzheimer disease and related dementias (ADRD) are especially prevalent among Medicare-Medicaid dual-eligible beneficiaries-the clinical complexity of ADRD amplifies the challenges of managing chronic conditions and accessing care for dual-eligible beneficiaries, and the need to navigate the fragmented Medicare-Medicaid benefits adds to patients' burdens. Little is known about how enrollment in dual-eligible special needs plans (D-SNPs) that coordinate Medicare and Medicaid coverage is associated with health outcomes for dual-eligible beneficiaries with ADRD. OBJECTIVE: To examine the associations between Medicare Advantage (MA) plan type and adverse medical events among dual-eligible beneficiaries with ADRD. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional analysis used MA encounter data from 2016 to 2019. Participants included dual-eligible, community-dwelling Medicare beneficiaries aged 65 years and older with ADRD who enrolled in MA plans in 50 US states and Washington, DC. Data were analyzed from January to November 2024. EXPOSURES: Enrollment in non-D-SNP Medicare Advantage plans and D-SNPs. The exposure variable for additional analyses included enrollment in fully integrated special needs plans (FIDE SNPs). MAIN OUTCOMES AND MEASURES: Preventable hospitalizations, 30-day all-cause readmissions, and avoidable emergency department (ED) visits. RESULTS: Analysis included a total of 121 145 patients in non-D-SNP plans with an enrollment of 173 662 patient-years (mean [SD] age, 81.8 [7.8] years
122 565 female [70.6%]
6078 Asian [3.5%], 34 150 Black [19.7%], 37 580 Hispanic [21.6%], 95 854 White [55.2%]) and 78 166 patients in D-SNP plans with an enrollment of 122 681 patient-years (mean [SD] age, 80.2 [8.0] years
87 329 female [71.2%]
10 530 Asian [8.6%], 33 280 Black [27.1%], 43 294 Hispanic [35.3%], 35 577 White [29.0%]). Dual-eligible enrollees with ADRD had a preventable hospitalization rate of 10.8% (95% CI, 10.3%-11.4%), a 30-day readmission rate of 22.3% (95% CI, 21.6%-22.9%), and an avoidable ED visit rate of 21.1% (95% CI, 20.3-21.9) in D-SNPs. These rates were 11.1% (95% CI, 10.7%-11.5%), 23.6% (95% CI, 22.9%-24.3%), and 20.8% (95% CI, 20.1%-21.6%) in non-D-SNP MA plans. There were no statistical differences in rates of preventable hospitalizations or avoidable ED visits between dual-eligible enrollees with ADRD in D-SNPs and those in non-D-SNP MA plans. Compared with non-D-SNPs, enrollees in FIDE SNPs had lower probabilities of preventable hospitalizations by 1.2 percentage points (95% CI, -2.7 to -0.2 percentage points) and 30-day readmissions by 7.2 percentage points (95% CI, -9.3 to -5.1 percentage points). CONCLUSIONS AND RELEVANCE: Dual-eligible beneficiaries with ADRD enrolled in D-SNPs and non-D-SNP MA plans had similar rates of adverse events. Dual-eligible beneficiaries with ADRD may benefit from enrollment in more coordinated MA plans, such as FIDE SNPs, by lowering unnecessary hospitalizations.