Purpose Blacks have as much as a four-fold incidence of end-stage renal disease (ESRD) when compared to whites. It is not known if the higher incidence of ESRD among blacks represents more rapid progression of kidney disease or better survival of black patients. We evaluated racial differences in survival among patients with kidney disease after acute myocardial infarction (AMI).
Methods The Cooperative Cardiovascular Project (CCP) linked administrative and medical record review data for a proportional sample of Medicare AMI admissions from 6,684 hospitals (March 4, 1994-June 30, 1995). Using the abbreviated Modified Diet in Renal Disease study equation to estimate glomerular filtration rate (GFR), we classified kidney function into 5 categories, GFR > 60, GFR 46-60, GFR 31-45, GFR 16-30 and GFR ≤ 15. We selected nondialysis, non-Hispanic black and white patients with incident AMI. Using logistic regression with generalized estimating equations to account for clustering within hospitals, we studied the association of race with 2-year mortality within each category of GFR after adjusting for illness severity, comorbidities, demographics, and treatment characteristics.
Results Among the 54,150 patients remaining after exclusions, blacks, compared to whites, were younger, more frequently female, and had more comorbidities. Blacks had higher mean APACHE II score and more frequently experienced a cardiac arrest. Blacks also had higher mean estimated GFR, 56.1 (SD 21.3), compared to whites, 53.5 (SD 25.1). The percent of patients dead 2 years after AMI did not differ significantly between blacks (38.1%) and whites (38.6%, p = .6). The odds of death 2 years after AMI for blacks vs. whites were lower within each successive category of kidney function (Table 1).
Conclusions Among patients with more severe kidney disease, black patients were less likely than whites to be dead 2 years after AMI, suggesting that the higher incidence of black patients with ESRD may result in part from better survival. Longitudinal studies are required to confirm this observation and to help alleviate racial disparities in kidney disease.