Blog | Monday, February 6, 2012

QD: News Every Day--Blacks have twice the rate of ESRD despite half the CKD of whites

End stage renal disease (ESRD) is higher in blacks than in whites, despite having less chronic kidney disease (CKD), researchers concluded, a difference that is explained in part by albuminuria.

The study compared the incidence of CKD among young adults over 20 years of follow-up in the community-based Coronary Artery Risk Development in Young Adults study. CARDIA was a prospective cohort study sponsored by the National Heart, Lung, and Blood Institute that recruited patients from Birmingham, Alabama; Chicago; Minneapolis; and Oakland, California.

Participants included 4,119 adults, 18 to 30 years old, with an estimated GFR (eGFR) greater than 60 ml/min per 1.73 m2 at baseline. CKD was defined as an eGFR less than 60 ml/min per 1.73 m2 and more than 25% decline in eGFR at study visits conducted 10, 15, and 20 years after baseline.

Results appeared in the Clinical Journal of the American Journal of Nephrology.

43 cases of CKD developed during follow-up, 29 (1.4%) among blacks and 14 (0.7%) among whites (P=0.02). The hazard ratio (HR) for developing CKD comparing blacks to whites was 2.56 (95% confidence interval [CI], 1.35 to 5.05). After further adjustment for body-mass index (BMI), systolic blood pressure, fasting plasma glucose, and high-density lipoprotein (HDL) cholesterol, the HR was 2.51 (95% CI, 1.25 to 5.05).

At the year 10 visit, the geometric mean albuminuria level was 8.2 mg/g (95% CI, 7.8 to 8.5) and 6.6 mg/g (95% CI, 6.4 to 6.8) among blacks and whites, respectively. The age- and sex-adjusted hazard ratio for developing CKD at year 15 or 20 for blacks versus whites was 2.14 (95% CI, 1.07 to 4.25). After further adjustment for covariates from the year 10 study visit, developing CKD at year 15 or 20 had an HR of 1.50 (95% CI, 0.71 to 3.16). Further adjustment for year 10 albumin-to-creatinine ratio reduced the hazard ratio to 1.12 (95% CI, 0.52 to 2.41).

It is possible that African Americans have more severe kidney disease that progresses to ESRD more quickly, the authors wrote, noting that six of the seven patients with ESRD in this study were black.

"This finding provides an important contrast to cross-sectional studies reporting a higher CKD prevalence among whites compared with African Americans" the concluded. "Much of this increased risk may be explained by the higher prevalence of albuminuria among African Americans."