THE EXCESS INCIDENCE OF DIABETIC END-STAGE RENAL-DISEASE AMONG BLACKS - A POPULATION-BASED STUDY OF POTENTIAL EXPLANATORY FACTORS

Objective.-To investigate whether the excess incidence of diabetic end-stage renal disease (ESRD) among African Americans could be explained by racial differences in putative ESRD risk factors. Design.-Population-based, ecologic study using the 1981 and 1982 Maryland Statewide Household Hypertension Survey for data on risk factor prevalence. Participants.-A total of 2.1 million adults residing within the boundaries of the Maryland Regional ESRD Registry, grouped by race and ZIP code into 26 subpopulations. Main Outcome Measure.-Incidence rates of treatment for diabetic ESRD between 1980 and 1985 from the Maryland Regional ESRD Registry by subpopulation. Results.-Between 1980 and 1985, 442 persons entered treatment for diabetic ESRD. At the level of the subpopulation, diabetic ESRD incidence was positively associated with black race (relative risk [RR], 3.42; 95% confidence interval [Cl], 2.84 to 4.13), prevalence of diabetes (RR, 2.35; 95% Cl, 1.92 to 2.87), prevalence of poorly controlled hypertension (RR, 1.80; 95% Cl, 1.45 to 1.86), lack of a regular source of health care (RR, 1.82; 95% Cl, 1.62 to 2.05), and lower socioeconomic status as indicated by lack of college education (RR, 1.41; 95% Cl, 1.32 to 1.52) (all, P<.0001). After adjusting for these risk factors, black race remained strongly associated with the overall incidence of diabetic ESRD (RR, 2.70; 95% Cl, 1.89 to 3.86; P<.0001). Further analyses suggested that this excess risk among blacks was confined to ESRD related to non-insulin-dependent diabetes (RR, 4.80; 95% Cl, 3.09 to 7.46; P<.0001); blacks were at no higher risk than were whites for ESRD related to insulin-dependent diabetes (RR, 0.90; 95% Cl, 0.52 to 1.55; P=.70). Conclusions.-These data suggest that the excess incidence of diabetic ESRD among blacks is not fully explained by a higher prevalence of diabetes or hypertension in blacks or by racial differences in age, socioeconomic status, or access to health care. Instead, they suggest an increased susceptibility to ESRD resulting from non-insulin-dependent diabetes among blacks as compared with whites.