Mortality Among Older Medical Patients at Flagship Hospitals and Their Affiliates.

Background: We define a "flagship hospital" as the largest academic hospital within a hospital referral region and a "flagship system" as a system that contains a flagship hospital and its affiliates. It is not known if patients admitted to an affiliate hospital, and not to its main flagship hospital, have better outcomes than those admitted to a hospital outside the flagship system but within the same hospital referral region.

Objective: To compare mortality at flagship hospitals and their affiliates to matched control patients not in the flagship system but within the same hospital referral region.

Design: A matched cohort study PARTICIPANTS: The study used hospitalizations for common medical conditions between 2018-2019 among older patients age ≥ 66 years. We analyzed 118,321 matched pairs of Medicare patients admitted with pneumonia (N=57,775), heart failure (N=42,531), or acute myocardial infarction (N=18,015) in 35 flagship hospitals, 124 affiliates, and 793 control hospitals.

Main Measures: 30-day (primary) and 90-day (secondary) all-cause mortality.

Key Results: 30-day mortality was lower among patients in flagship systems versus control hospitals that are not part of the flagship system but within the same hospital referral region (difference= -0.62%, 95% CI [-0.88%, -0.37%], P<0.001). This difference was smaller in affiliates versus controls (-0.43%, [-0.75%, -0.11%], P=0.008) than in flagship hospitals versus controls (-1.02%, [-1.46%, -0.58%], P<0.001; difference-in-difference -0.59%, [-1.13%, -0.05%], P=0.033). Similar results were found for 90-day mortality.

Limitations: The study used claims-based data.

Conclusions: In aggregate, within a hospital referral region, patients treated at the flagship hospital, at affiliates of the flagship hospital, and in the flagship system as a whole, all had lower mortality rates than matched controls outside the flagship system. However, the mortality advantage was larger for flagship hospitals than for their affiliates.