Coordinating Care for Better Outcomes: An Analysis of 30-Day All-Cause Readmissions and Accountable Care Organization Attribution

Abstract

This study explored a large segment of Medicare claims data to evaluate the association between Accountable Care Organization (ACO) attribution and 30-day all-cause hospital readmissions. ACOs deliver value-based care to attributed patient populations, aiming to enhance care coordination and transitional care outcomes. Initiatives such as the Medicare Shared Savings Program (MSSP) incentivize health care systems to reduce readmissions and the total cost of care. The study included all Medicare inpatient discharges across 50 US states from January 1, 2022, to December 1, 2024. The primary measure of interest was 30-day all-cause readmissions. Hospitalizations for ACO-attributed beneficiaries (readmitted vs. not readmitted) were compared with hospitalizations for non-ACO-attributed beneficiaries. Subgroup and sensitivity analyses were conducted to explore ACO readmission performance with cohorts of beneficiaries with higher levels of clinical complexity and single or multiple hospital admissions. MSSP ACO beneficiaries had a 6% lower rate of 30-day all-cause readmissions. When restricting the cohorts to beneficiaries with higher levels of clinical complexity, MSSP ACO participants had significantly lower readmission rates. Sensitivity analyses adjusting for unequal sample sizes, differences in clinical complexity, and excess zeros (statistical overinflation) indicated that despite the positive effect of multiple hospitalizations, assignment to an ACO was significantly associated with lower readmission risk. The ACO care delivery model is a high-performing care coordination model that exemplifies best practices in addressing transitional care challenges, providing actionable insights for other health care organizations seeking to advance their transitional care strategies within value-based programs.