Risk Factors for Incident CKD in Black and White Americans: The REGARDS Study

Rationale & Objective: Little information exists on the incidence of and risk factors for chronic kidney disease (CKD) in contemporary US co-horts and whether risk factors differ by race, sex, or region in the United States.Study Design: Observational cohort study.Setting & Participants: 4,198 Black and 7,799 White participants aged at least 45 years, recruited from 2003 through 2007 across the continental United States, with baseline estimated glomerular filtration rate (eGFR) >60 mL/min/1.73 m2 and eGFR assessed again approximately 9 years later.Exposures: Age, sex, race (Black or White), re-gion ("stroke belt" or other), education, income, systolic blood pressure, body mass index, dia-betes, coronary heart disease, hyperlipidemia, smoking, and albuminuria.Outcomes: (1) eGFR change and (2) incident CKD defined as eGFR <60 mL/min/1.73 m2 and & GE;40% decrease from baseline or kidney failure.Analytical Approach: Linear regression and modified Poisson regression were used to determine the association of risk factors with eGFR change and incident CKD overall and stratified by race, sex, and region.Results: Mean age of participants was 63 & PLUSMN; 8 (SD) years, 54% were female, and 35% were Black. After 9.4 & PLUSMN; 1.0 years of follow-up, CKD developed in 9%. In an age-, sex-, and race-adjusted model, Black race ([3 = -0.13; P < 0.001) was associated with higher risk of eGFR change, but this was attenuated in the fully adjusted model ([3 = 0.02; P = 0.5). Stroke belt residence was independently associated with eGFR change ([3 = -0.10; P < 0.001) and incident CKD (relative risk, 1.14 [95% CI, 1.01-1.30]). Albuminuria was more strongly associated with eGFR change ([3 of -0.26 vs -0.17; P = 0.01 for interaction) in Black compared with White participants. Results were similar for incident CKD.Limitations: Persons of Hispanic ethnicity were excluded; unknown duration and/or severity of risk factors.Conclusions: Established CKD risk factors accounted for higher risk of incident CKD in Black versus White individuals. Albuminuria was a stronger risk factor for eGFR decrease and inci-dent CKD in Black compared with White in-dividuals. Living in the US stroke belt is a novel risk factor for CKD.