Risk Selection and Care Fragmentation at Medicare Accountable Care Organizations for Patients With Dementia

Background: Patients with dementia are a growing and vulnerable population within Medicare. Accountable care organizations (ACOs) are becoming Medicare's dominant care model, but ACO enrollment and care patterns for patients with dementia are unknown. Objective: The aim of this study was to compare differences in ACO enrollment for patients with versus without dementia, and in risk profiles and ambulatory care among patients with dementia by ACO enrollment status. Research Design: Cohort study assessing the relationships between patient dementia, following-year ACO enrollment, and ambulatory care patterns. Subjects: A total of 13,362 (weighted: 45, 499,049) person-years for patients [2761 (weighted: 6,312,304) for dementia patients] ages 65 years and above in the 2015-2019 Medicare Current Beneficiary Survey. Measures: We assessed differences in ACO enrollment rates for patients with versus without dementia, and in dementia-relevant ambulatory care visit rates and validated care fragmentation indices among patients with dementia by ACO enrollment status. Results: Patients with versus without dementia were less likely to be enrolled in (38.3% vs. 44.6%, P<0.001), and more likely to exit (21.1% vs. 13.7%, P<0.01) ACOs. Among patients with dementia, those enrolled versus not enrolled in ACOs had a more favorable social and health risk profile on 6 of 16 measures (P<0.05). There were no differences in rates of dementia-relevant, primary, or specialty care visits. ACO enrollment was associated with 45.7% higher wellness visit rates (P<0.001), and 13.4% more fragmented primary care (P<0.01) spread across 8.7% more distinct physicians (P<0.05). Conclusion: Medicare ACOs are less likely to enroll and retain patients with dementia than other patients and provide more fragmented primary care without providing additional dementia-relevant ambulatory care visits.