The joint effects of race and age on the risk of end-stage renal disease.

Abstract

To describe the race-age joint effects on the end-stage renal disease (ESRD) risk, data for blacks and whites from the United States Renal Data System were analyzed. By using data for 1988 it was found that at each age above 14 the risk of ESRD was more than two fold higher for blacks. Except for ages 64 to 79 years among blacks, the risk of ESRD was higher for men. An additive model with ages 20-24 as the referent revealed that for black men, 35 to 59 years, and for black women, 45 to 74 years, over 70 percent of ESRD cases would not occur had the effects of race been independent of the age effects. The results support important roles for hypertensive and diabetic nephropathies in explaining these race-age joint effects on the ESRD risk. By using data for the period 1987-1990 it was found that the black/white incidence rate ratios (B/W RR) for ESRD attributed to hypertension (ESRD-HT) were more striking for ages 20 to 40 (especially among men), a finding that cannot be explained by national estimates of prevalence of hypertension. This suggests that kidney damage as a result of hypertension is more severe for younger blacks (especially men) than for younger whites. Data for 1988-1991 revealed that, by contrast to ESRD-HT, the B/W RR for ESRD-DM was more striking for ages 40 or above, particularly among women. A relatively small B/W RR for ESRD-DM observed for ages 20 to 40 years as well as the increase with age in the B/W RR for ESRD-DM could not be fully explained by prevalence of diabetes. It is here proposed that a relatively small B/W gap in ESRD-DM among younger adults could be partly due to an increased risk of premature death due to cardiovascular disease before reaching ESRD in diabetic blacks. The race and age effects here described are consistent with the idea that interactions involving race-related risk factors and aging play a role in the pathogenesis of ESRD. Testable hypotheses to explain the patterns of race-age joint effects on the ESRD risk are proposed.