Income-based disparities in the development of infectious complications following elective isolated coronary artery bypass grafting

BACKGROUND: Infections following cardiac surgery carry a significant mortality burden. While traditional factors, including emergency surgery, diabetes, and smoking, have been linked with increased risk of infection following coronary artery bypass grafting, recent evidence highlights nontraditional factors, including social determinants of health. In the present work, we characterized the association of low-income status with perioperative infection risk in a national cohort of coronary artery bypass grafting recipients. METHODS: All elective adult (≥18 years) hospitalization records entailing isolated coronary artery bypass grafting were tabulated from the 2016-2022 Nationwide Readmissions Database. Patients were grouped into income quartiles according to the ZIP code-derived household income. Infections of interest included wound, respiratory, and gastrointestinal infections, among others. Multivariable regression models were developed to determine the association between income and outcomes. RESULTS: Of 543,869 admissions for coronary artery bypass grafting, 134,490 (25.3%) were classified as low income, whereas 95,751 (18.7%) were classified as high income. Low-income patients were younger (67 [60-73] vs 68 [61-74], P < .001), more commonly female (25.9 vs 16.8%, P < .001), and less likely to receive treatment at a metropolitan-teaching hospital (77.4% vs 90.0%, P < .001) relative to high-income patients. Following doubly robust risk adjustment, low income remained associated with increased risk for sepsis and bacteremia (adjusted odds ratio, 1.55; 95% confidence interval, 1.36-1.77), wound (adjusted odds ratio, 1.52; 95% confidence interval, 1.21-1.90), and gastrointestinal (adjusted odds ratio, 1.50; 95% confidence interval, 1.17-1.92) infections. Moreover, low income was associated with higher odds of mortality (adjusted odds ratio, 1.67; 95% confidence interval, 1.46-1.92). CONCLUSION: Low-income status is associated with increased risk of infection among coronary artery bypass grafting recipients. While income is not a modifiable risk factor, further research should examine underlying mechanisms and identify areas for quality improvements, including better longitudinal access to care.