Socioeconomic status and end-stage renal disease in the United States. The incidence of treated end-stage renal disease (ESRD) varies markedly according to age, race, sex, and geographic characteristics of the population. We asked whether some of the variability in the incidence of treated ESRD (t-ESRD) was associated with differences in socioeconomic status and whether socioeconomic status could explain some of the effects of race on t-ESRD incidence. Demographic characteristics of incident cases of t-ESRD from the years 1983 to 1988 were obtained from the U.S. Renal Data System, which registers most treated cases of ESRD. The average race specific, per capita income of the county of residence, as determined from the Bureau of Health Professions Area Resource File, was used as a surrogate measure of socioeconomic status. The incidence of t-ESRD for individuals <60 years of age was modeled as a log-linear function of socioeconomic and demographic factors, including age, sex, the urban fraction of the county of residence, and the census geographic region. For both Whites and Blacks, the incidence of t-ESRD was higher for males and older age groups, as expected. In general, the incidence of t-ESRD was inversely related to income level. For Whites, the relative risk was 1.21 for income of $0 to 10,000, 1.11 for $10,000 to 15,000, 1.00 for $15,000 to 20,000 (reference), 0.89 for $20,000 to 25,000, and 0.77 for income > $25,000. For Blacks, the relative risk was 1.10 for income of $0 to 10,000, 1.20 for $10,000 to 15,000, 1.00 for $15,000 to 20,000 (reference), 0.81 for $20,000 to 25,000, and 0.69 for income > $25,000. At the lowest income level, the incidence of t-ESRD was lower than would be projected by a linear model for Blacks. The high absolute incidence of t-ESRD among Blacks was only partially explained by lower socioeconomic status. The incidence of t-ESRD varies by approximately 40 to 50% over the range of average per capita income levels but average county income does not fully explain the effects of race, sex, or age.
