Differences in the patterns of age-specific black/white comparisons between end-stage renal disease attributed and not attributed to diabetes

Abstract

To assess differences in the patterns of age-specific black/white comparisons between end-stage renal disease (ESRD) attributed to diabetes (ESRD-DM) and not attributed to diabetes (ESRD-NON-DM), data for subjects 20 to 79 years of age reported by the US Renal Data System as incident cases of ESRD during 1988 to 1991 were analyzed. While the black to white incidence rate ratio (B/W RR) for ESRD-NON-DM peaked in patients before the age of 40 years, the most striking B/W RRs for ESRD-DM were observed in patients older than 40 years. This study also explored evidence supporting the hypothesis that an increased risk of premature death attributed to cardiovascular disease (CVD death) in black patients, alone or in combination with black/white differences in prevalence of diabetes, influences the pattern of age-specific black/white ESRD-DM comparisons. By using estimates of the diabetic population as denominators for the rates, the incidence or ESRD-DM remained much higher in black patients than in white patients for those aged 45 years or above. However, the incidence of ESRD-DM for patients aged below 45 years was found to be significantly ( P < 0.05) lower (B/W RR = 0.6) for black male diabetic patients and slightly, yet significantly, higher ( P < 0.05; B/W RR = 1.1) for black female diabetic patients than for their white counterparts. Therefore, prevalence of diabetes could not fully explain the pattern of age-specific B/W RR for ESRD-DM. To compare black and white patients with regard to their age-specific risks of CVD death (ie, acute myocardial infarction and cerebrovascular diseases), data reported by the US Department of Health and Human Services from 1987 to 1989 were analyzed. By contrast to the late peak in the B/W RR for ESRD-DM, the B/W RR for CVD death was more striking for patients aged below 40 years. These findings are consistent with the hypothesis that the smaller B/W RR for ESRD-DM observed for patients aged below 40 years is partly mediated by a higher risk of CVD death before reaching ESRD in younger black patients. Follow-up studies to compare the risks of major outcomes, such as CVD death and ESRD, between black and white patients newly diagnosed with diabetes should increase our understanding of the extent to which competing risks influence the pattern of age-specific black/white ESRD-DM comparisons.