ORLANDO, Fla.—Obesity and metabolic syndrome may influence CKD measures differently among African Americans and whites, according to a study. The finding could explain differences in long-term kidney and cardiovascular outcomes.
The study, by Andrew S. Bomback, MD, of the Columbia University College of Physicians and Surgeons in New York, and collaborators, showed that obese white individuals were more likely to have a lower estimated glomerular filtration rate (eGFR) and advanced CKD. In addition, obese African Americans, with and without metabolic syndrome, had significantly higher rates of abnormal urinary albumin excretion and earlier stage CKD.
Dr. Bomback’s group studied three cohorts of patients who participated in the Kidney Early Evaluation Program (KEEP). The National Kidney Foundation (NKF) developed KEEP to provide screening for early CKD in individuals aged 18 years and older with diabetes, hypertension, or a family history of kidney disease, diabetes, or hypertension.
Cohort 1 consisted of 37,107 obese subjects (body mass index of 30 kg/m2 or higher. Cohort 2 included 16,693 subjects from cohort 1 with cholesterol and triglyceride data available since May 1, 2005. Cohort 3 included 2,030 individuals from cohort 1 with an eGFR below 60 mL/min/1.73 m2 and data on parathyroid hormone (PTH), calcium, and phosphorus available since November 1, 2005.
In cohort 1, 48% of participants were African-American and 52% were white. Whites were more likely than African Americans to have components of the metabolic syndrome, including hypertension (87.1% vs. 84.9%), dyslipidemia (81.6% vs. 66.7%), and diabetes (42.7% vs. 34.9%).
Obese whites were 42% less likely than obese African Americans to have CKD stages 3-5, according to data presented here at the NKF’s 2010 Spring Clinical Meetings. Obese African Americans were 60% more likely to have microalbuminuria, 61% more likely to have macroalbuminuria, and 54% more likely to have CKD stages 1-2, after adjusting for confounding variables.
Furthermore, among obese subjects with CKD stages 3-5, 32.4% of African Americans had anemia compared with 14.1% of whites. Secondary hyperparathyroidism was present in 66.2% and 46.6% of African Americans and whites, respectively.