Background: Studies have demonstrated that chronic kidney disease (CKD), especially its last stage - end-stage renal disease (ESRD) - is not only an independent risk factor for coronary artery disease (CAD), but it also worsens survival prognosis in CAD patients. It remains unclear whether racial disparities affect the outcomes of coronary revascularization procedures - coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) - in CAD patients with ESRD (CAD-ESRD).
Study Objectives: (1) to investigate comparative effectiveness of CABG and PCI on in-hospital mortality outcomes in CAD-ESRD patients and (2) to investigate racial disparities in the utilization and in-hospital mortality outcomes of CABG and PCI in CAD-ESRD patients.
Methods: We conducted a retrospective cohort study of in-hospital mortality in 23,519 CAD-ESRD patients [mean+SD age: 65.4+11.6 years; 62.2% (14,626 of 23,519) males] after CABG and PCI during 2007-2011. Patient race was defined as white, black, Asian, or Native American. In-hospital patient death was a binary outcome of interest. Adjusted odds ratios were obtained from multivariable logistic regression (MLR), adjusted for known clinical, demographic, and socio-economic covariates.
Results: In the covariate-adjusted MLR analysis, post-PCI in-hospital mortality in CAD-ESRD patients was significantly lower than post-CABG mortality (adjusted OR = 0.47, 95% CI: 0.41-0.53, p<0.001). Post-procedure mortality was associated with emergency room (ER) admission (adjusted OR 1.62, 95% CI: 1.44-1.83, p<0.001), older age (3.2% increase for each year, 95% CI: 2.6-3.8%, p<0.001), and higher severity of co-existing conditions other than ESRD measured by the Elixhauser Comorbidity Index (8.5% increase for each point increase in the modified Elixhauser-Walraven score, 95% CI: 7.5-9.5%, p<0.001). Blacks were more likely to undergo an ER admission (48.4%) than Asians (46.0%), Native Americans (43.2%) or whites (42.4%, p<0.05, with multiple comparison correction). In the adjusted MLR analysis, race was not a statistically significant independent predictor of post-procedure mortality. C-statistic for the MLR was 0.729.
Conclusions: Our results suggest that in-hospital post-PCI mortality in CAD-ESRD patients is lower than post-CABG mortality. Racial disparities in ER admissions - a demonstrated predictor of post-procedure mortality in these patients - may reflect the underlying racial disparities in access to and utilization of primary care. Further studies investigating disparities in CAD-ESRD mortality are warranted.