High-risk care management impact on Medicaid ACO utilization and spending.

Objectives: States are experimenting with accountable care organization (ACO) contracts to slow Medicaid spending growth. There is limited information on how ACOs have impacted expenditures in Medicaid, which includes a relatively heterogenous population with less spending compared with Medicare. This study aimed to evaluate the impact of high-risk care management on spending and utilization within Massachusetts' largest Medicaid ACO.

Study design: This observational study analyzed Medicaid claims data from Massachusetts' largest Medicaid ACO utilizing staggered program entry from 2016 to 2021 (n = 158,441 total beneficiaries). It included adults aged 18 to 64 years with multiple chronic conditions and used a claims-based algorithm for participant selection. We examined spending and clinical event rates of those participating and not yet participating in a high-risk care management program. Between 2016 and 2021, 2479 beneficiaries were identified as high risk and entered the program.

Methods: The study utilized a difference-in-differences approach with linear regression models to assess the impact of care management. The analysis accounted for time-stable and time-changing covariates, including comorbidity levels and age.

Results: Participation in the program for 7 or more months was associated with a $243 reduction in monthly spending compared with similar beneficiaries who had not yet started the program (95% CI, -$479 to -$6). There also were comparable reductions in emergency department visit and hospitalization rates.

Conclusions: These early ACO data findings suggest that upstream care management of high-risk individuals may represent a viable approach for slowing Medicaid spending growth.