Abstract 208: Racial Disparities Affect In-hospital Mortality Rates Following Coronary Artery Bypass Grafting Among Patients With End-stage Renal Disease

Abstract

Background: Coronary artery disease (CAD) is the leading cause of death among patients with end-stage renal disease (ESRD). ESRD patients are at a higher risk of coronary artery bypass grafting (CABG) perioperative mortality than their non-ESRD counterparts. The extent and the mechanisms of racial disparities in post-CABG outcomes among ESRD patients remain unclear. Hypothesis: We hypothesized that post-CABG in-hospital mortality in ESRD patients is affected by patients’ race. Methods: We conducted a retrospective cohort study of post-CABG in-hospital mortality among 6,590 CAD patients with ESRD during the period of 2007-2011 [mean±SD age: 64.8±11.13 years; 67.8% (4,468 of 6,590) males]. Most of the patients were white (66.0%; 4,347 of 6,590), 21.7% (1,432 of 6,590) were black, 11.0% (725 of 6,590) were Asian, and 1.3% (86 of 6,590) were American Indian. In-hospital death was defined as a binary outcome (discharged alive or deceased) due to a relatively short length of stay. Adjusted odds ratios (OR) for in-hospital death after CABG in relation to patients’ race, adjusting for major clinical and demographic covariates, were obtained with multivariable logistic regression. Results: Unadjusted (crude) post-CABG in-hospital mortality rate in ESRD patients was 8.8% (579 of 6,590). Mortality rate was higher among patients admitted through emergency department (ED) than non-ED admitted patients: mortality rates 10.2% (221 of 2,169 ED admitted) and 8.1% (358 of 4,421 non-ED admitted), respectively ( P =0.0048). Deceased patients had more severe comorbidities and higher Elixhauser-Walraven comorbidity scores (12.6±6.7 points among deceased and 9.2±6.0 points among discharged alive; P <0.001). Blacks were more likely to experience an ED admission [with 39.2% (561 of 1,432) of blacks being ED admitted] than Asians (34.6%; 251 of 725 were ED admitted), whites (30.6%; 1,331 of 4,347 were ED admitted) or American Indians (30.2%; 26 of 86 were ED admitted). In the adjusted multivariable analysis, black patients had statistically significantly higher odds of post-CABG death than Asian patients (adjusted OR, 1.58; 95% CI, 1.09-2.30; P =0.0169). However, neither white patients (adjusted OR, 1.35; 95% CI, 0.96-1.89; P =0.0860) nor American Indian patients (adjusted OR, 2.16; 95% CI, 0.95-4.94; P =0.0676) had a statistically significantly higher risk of post-CABG death compared to Asian patients. Conclusions: Our findings indicate that racial disparities affect post-CABG in-hospital mortality rates in CAD patients with ESRD. Post-CABG mortality rate disparities may be attributed, at least partially, to racial disparities in severity of comorbidity and the type of admittance. Further studies investigating more detailed mechanisms responsible for these disparities are warranted.