Hospital-Medicare Advantage Vertical Integration and Cardiopulmonary Care in Integrated Hospitals.

Importance: The rate of health care payer and practitioner consolidation is increasing, with limited assessment of hospital-Medicare Advantage (MA) plan vertical integration. Little is known about whether aligned incentives between hospitals and MA contracts may improve care coordination and outcomes. Objective: To investigate the association between hospital-MA contract vertical integration and cardiopulmonary outcomes. Design, Setting, and Participants: This cross-sectional study included MA enrollees admitted for acute myocardial infarction, heart failure, or pneumonia between January 2015 and December 2022. Admissions that occurred in a hospital that owns an MA plan were matched to comparison admissions based on the propensity score of being enrolled in an integrated MA contract. Analysis was conducted between December 1, 2024, and March 20, 2025. Exposure: Admissions were categorized as nonintegrated (MA contract not owned by a hospital), partially integrated (hospital-owned MA contract but admission at nonaffiliated hospital), or fully integrated (admitted at a hospital that owns MA contract). Main Outcomes and Measures: Generalized linear models adjusted for demographics, clinical features, and hospital, zip code, year, and diagnosis-related group fixed effects. Care intensity was measured using length of stay and intensive care unit (ICU) use. Clinical outcomes were inpatient mortality, 30-day postdischarge mortality, and 30-day postdischarge readmission. Results: The sample consisted of 1 057 715 admissions, of which 234 587 were partially integrated and 118 017 were fully integrated. After matching, the mean (SD) age was 78.0 (9.9) years for participants in the nonintegrated group, 78.0 (9.9) years for those in the partially integrated group, and 78.0 (9.8) years in the fully integrated group; 48.8% were female in the nonintegrated group, 48.9% in the partially integrated group, and 48.9% in the fully integrated group. Fully integrated admissions had significantly shorter lengths of stay (adjusted difference, -0.24 days; 95% CI, -0.31 to -0.18 days vs nonintegrated; -0.28 days; 95% CI, -0.37 to -0.18 days vs partially integrated) and lower rates of ICU use (-1.17 percentage points; 95% CI, -1.82 to -0.52 percentage points vs nonintegrated; -1.42 percentage points; 95% CI, -2.44 to -0.40 percentage points vs partially integrated), inpatient mortality (-0.61 percentage points; 95% CI, -0.88 to -0.34 percentage points vs nonintegrated), 30-day postdischarge mortality (-0.87 percentage points; 95% CI, -1.30 to -0.44 percentage points vs nonintegrated), and 30-day postdischarge readmission (-0.78 percentage points; 95% CI, -1.30 to -0.26 percentage points vs nonintegrated). Conclusions and Relevance: In this study, among patients hospitalized with myocardial infarction, heart failure, or pneumonia, enrollment in a hospital-owned MA contract along with admission to the affiliated hospital was associated with a shorter length of stay, less ICU use, and lower mortality and readmission rates.