BACKGROUND: Differences in the quality of hospitals where Black and White patients receive coronary artery bypass grafting (CABG) surgery have been documented. We examined the contributions of physician networks to the gap. METHODS: This was a cross-sectional study of all Medicare fee-for-service Black and White patients undergoing elective CABG during 2017 to 2019
the primary care physicians and cardiologists treating them for 12 months before surgery (the patients' physician network)
and CABG-performing hospitals within 100 miles of each patient. We measured the strength of ties between treating physicians and hospitals as the number of shared prior CABG patients (24 months before surgery). Conditional logit models assessed the relationship between race, prior physician-hospital ties, and receiving CABG at hospitals with minimum versus the median-above-minimum mortality difference, while accounting for home-to-hospital distances. RESULTS: The study included 76 376 patients
5.1% were Blackpatients. Black and White patients were admitted to similar mortality hospitals (3.1% versus 3.1%
CONCLUSIONS: Despite the improvement of previously described disparities in the quality of hospitals treating Black and White patients, Black patients remain less likely to undergo CABG at their lowest available mortality hospitals, possibly due to suboptimal physician referrals.