Low Income and Albuminuria Among REGARDS (Reasons for Geographic and Racial Differences in Stroke) Study Participants

• Authors: Deidra C. Crews, Johns Hopkins University; William McClellan, Emory University; David A. Shoham, Loyola University; Liyan Gao, University of Alabama at Birmingham; David G. Warnock, University of Alabama at Birmingham; Suzanne Judd, University of Alabama at Birmingham; Paul Muntner, University of Alabama at Birmingham; Edgar R. Miller, Johns Hopkins University; Neil R. Powe, University of California San Francisco
• Journal Title: American Journal of Kidney Diseases
• Volume: Volume 60, Number 5
• Publisher: Elsevier: 12 months | 2012-11-01, Pages 779-786
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1053/j.ajkd.2012.05.010
• Subjects: Biology, Neuroscience; Health Sciences, Public Health; Health Sciences, Epidemiology
• Keywords: Race; Albuminuria; Poverty; Chronic kidney disease (CKD); Socioeconomic status; Disparity

Abstract

Background: Albuminuria is an important risk factor for progressive CKD and is more prevalent among black than among white adults. We sought to determine the association between low income and albuminuria, and if this association differs for blacks and whites. Study Design: Cross-sectional study. Setting & Participants: 9,144 black and 13,684 white U.S. adults aged 45 years and older in the population-based REasons for Geographic and Racial Differences in Stroke (REGARDS) study. Predictors: Self-reported annual household income category (≥$75,000, 35,000 – $74,999, $20,000 – $34,999, and <$20,000); black and white race. Outcomes & Measurements: Albuminuria defined as high (30 to 300 mg/g) or very high (>300 mg/g) urinary albumin-creatinine ratio (ACR). Multinomial logistic regression used to examine the race-stratified association between categories of income and albuminuria (normal, high, or very high ACR). Results: Overall, geometric mean ACR was 10.2 mg/g, and was higher for blacks (11.8 mg/g) than for whites (9.3 mg/g), p <0.001. Lower income was associated with a higher prevalence of albuminuria for both whites and blacks in unadjusted analyses. After adjustment for demographics, lifestyle factors, comorbid illnesses and estimated glomerular filtration rate, there was a trend towards a stronger association between lower income levels and high ACR among blacks [ORs of 1.38 (95% CI, 1.07 – 1.77), 1.36 (95% CI, 1.05 – 1.75), and 1.58 (95% CI, 1.21–2.05), for income levels of $35,000 – $74,999, $20,000 – $34,999, and <$20,000, respectively; reference group is those with income ≥$75,000] compared to whites [ORs of 0.95 (95% CI, 0.81 – 1.12), 0.95 (95% CI, 0.79 – 1.14), and 1.26 (95% CI, 1.02 – 1.55), respectively]; P interaction 0.08 between race and income. Results were similar for very high ACR, and subgroups of participants with diabetes or hypertension. Limitations: Cross-sectional design; not all REGARDS participants provided their annual income. Conclusions: Lower income may be more strongly associated with albuminuria among blacks than among whites, and may be a determinant of racial disparities in albuminuria.