Background: Individual-level socioeconomic status (SES) has been found to be associated inversely with progressive chronic kidney disease (CKD); the effect of area-level SES on progressive CKD is less known. We conducted a cohort study of 12,856 Atherosclerosis Risk in Communities Study participants to examine the independent risk for progressive CKD associated with living in a low SES area.
Methods: Progressive CKD is defined as a creatinine level elevation of 0.4 mg/dL or greater (> or = 35 micromol/L) during a 9-year follow-up, hospitalization for CKD, or death. Area-level SES was characterized by using measures of income, wealth, education, and occupation for 1990 US Census block groups of residence.
Results: Age- and center-adjusted incidence rates (per 1,000 person-years) of progressive CKD by quartiles of area-level SES score showed increasing rates with decreasing SES for African-American women: quartile 1 (Q1; low) = 11.1, Q2 = 10.5, Q3 = 6.4, and Q4 = 7.1 and white men: Q1 = 6.6, Q2 = 4.8, Q3 = 4.0, and Q4 (high) = 3.5, but not for African-American men or white women. Cox proportional hazards models showed that living in the lowest versus the highest SES-area quartile was associated with a 60% greater risk for progressive CKD in white men after adjusting for age, center, baseline creatinine level, body mass index, and individual-level SES (hazard ratio, 1.6; 95% confidence interval, 1.0 to 2.5). This risk and trend persisted after adjusting for such potential mediators as health awareness, health care access, and behavioral and physiological factors. We found no significant association of progressive CKD risk and area SES in white women, African-American women, or African-American men after adjustment.
Conclusion: For white men, living in a low SES area is independently associated with greater risk for progressive CKD. Future research is needed to examine this association, considering the disparate effects found by race/sex groups.