Socioeconomic status and the incidence of ESRD

Background: Persons of low socioeconomic status (SES) may be at increased risk of end-stage renal disease (ESRD). This study examines the association between SES and incidence of ESRD caused by all primary renal diseases and caused by 3 diseases that differ in the availability of effective treatment: diabetes mellitus, lupus nephritis, and autosomal dominant polycystic kidney disease (ADPKD). Study Design: Retrospective cohort study. Setting & Participants: Adults with incident ESRD in the United States from January 1, 1996, to June 30, 2004 (N = 747,556). Predictor: SES, based on characteristics of the patient's ZIP code of residence. Outcomes: Incidence of ESRD. Results: In all sex-race groups, the incidence of ESRD caused by all primary renal diseases was greatest in those in the lowest SES score quartile and decreased progressively with higher SES. For example, for white women, the incidence of ESRD was 388.9 per million in the lowest quartile of SES and 200.8 per million in the highest quartile of SES (relative risk, 1.92; 95% confidence interval, 1.89 to 1.95). However, this association differed among patients with primary renal diseases. There were strong associations between SES and ESRD caused by diabetes mellitus, weaker associations for ESRD caused by lupus nephritis, and generally no associations for ESRD caused by ADPKD. For example, for white women, relative risks of ESRD in the lowest compared with the highest SES quartile were 2.84 for ESRD caused by diabetes mellitus, 1.63 for ESRD caused by lupus nephritis, and 1.27 for ESRD caused by ADPKD. Limitations: Use of an area-based measure of SES. Conclusions: The strength of the association between SES and ESRD differs among patients with diabetes mellitus, lupus nephritis, and ADPKD, suggesting that socioeconomic factors act differently in the progression of chronic kidney disease in these conditions.