Referral Networks, Racial Inequity, and Hospital Quality for Open Heart Surgery.

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%; P=0.07), but Black patients lived closer to lower-mortality hospitals than White patients (mean hospital mortality within median travel distance, 2.5% versus 2.7%; P<0.001). Black patients were treated less often at the lowest-mortality hospitals overall and within the median travel distance (10.5% versus 13.9% and 37.4% versus 45.1%; P<0.001 for both). In conditional logit models, the Black-White risk ratio of using hospitals with median versus lowest mortality was 1.02 ([95% CI, 0.98-1.06]; P=0.18) in models including only race and hospital mortality; 1.07 ([95% CI, 1.01-1.13]; P<0.001) in models adding home-to-hospital distances; and 1.06 ([95% CI, 0.96-1.16]; P=0.11) in models also accounting for physician-hospital ties.

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.