BACKGROUND: We aimed to investigate the geographic variation of academic medical centers (AMCs) across different healthcare markets and the impact on surgical outcomes in nearby non-AMCs. STUDY DESIGN: Patients who underwent major surgery between 2016 and 2021 were identified from the Medicare Standard Analytic Files. Healthcare markets were delineated using Dartmouth Atlas hospital referral regions. Multivariable regression was used to examine the association between the presence of market-level AMCs and surgical outcomes in neighboring non-AMCs. RESULTS: A total of 388,431 Medicare beneficiaries underwent major surgery (coronary artery bypass grafting: 97,346, 25.1%
abdominal aortic aneurysm repair: 67,000, 17.3%
pneumonectomy: 30,500, 7.9%
pancreatectomy: 5,341, 1.4%
colectomy: 188,244, 48.5%) at 2,757 non-AMCs. Median age was 74 years (interquartile range 70 to 80 years), and roughly one-half of patients were men (215,569, 55.5%). Notably, 43.1% of individuals underwent surgery in markets with low AMC presence, 48.0% in markets with moderate AMC presence, and 8.9% in markets with high AMC presence. On multivariable analysis, compared with low AMC markets, high AMC presence was associated with decreased risk of extended length of stay (-1.51%, 95% CI -2.03 to -1.00
p <
0.001), postoperative complications (-1.20%, 95% CI -1.76 to -0.65
p <
0.001), 90-day readmission (-2.39%, 95% CI -2.90 to -1.88
p <
0.001), and mortality (-0.64% 95% CI -0.98 to -0.30
p <
0.001). Additionally, high AMC market presence was associated with a 2.93% (-2.93%, 95% CI -3.17 to -2.68
p <
0.001) decrease in expenditures for the index surgical procedure. CONCLUSIONS: High market presence of AMCs was associated with lower morbidity and mortality rates at nearby non-AMCs. The influence of AMCs on clinical outcomes likely extends beyond direct patient care, indicating spillover effects of AMCs on outcomes for patients in neighboring non-AMCs.