Study: CKD Outcomes Differ in African Americans

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Progression to ESRD more likely than CVD death in African Americans with hypertension-related CKD.

PHILADELPHIA—African Americans with hypertension-related CKD may be more likely to progress to end-stage renal disease (ESRD) than die from cardiovascular disease (CVD), the opposite of what has been reported for other CKD populations in many studies, researchers conclude.

The findings come from the African American Study of Kidney Disease (AASK) Cohort Study (2000-2007), which followed the original AASK Trial (1996-2001). Of the 1,094 eligible patients from the original trial, 691 were enrolled in the subsequent cohort study.

The patients, who had hypertensive nephrosclerosis, received intensive follow-up to keep their BP at a target level of less than 130/80 mm Hg. The mean age of patients at the start of the study in 1996 was 55 years; they were followed for 11 years.

The investigators observed four cases of ESRD (permanent loss of kidney function requiring dialysis or transplantation) for each 100 patient-years of follow-up. By comparison, the rate of CVD events was 3.2 per 100 patient-years and the risk of death from CVD was 0.8 per 100 patient-years. Of the 74 deaths that occurred during the AASK Cohort Study period, more than 60% were from causes other than CVD.

“The AASK trial and the subsequent cohort study allow the medical community to gain a broader understanding of incident cardiovascular disease and mortality during long-term follow-up in an entirely African American population with nondiabetic hypertensive nephrosclerosis,” said study investigator Tahira P. Alves, MD, a nephrology fellow at Vanderbilt University in Nashville. He presented findings here at the American Society of Nephrology's Renal Week conference.

A limitation of the cohort study is that the primary goal of the original AASK trial was to detect changes in kidney function, ESRD, and/or risk of death. Cardiovascular events were measured as a secondary outcome. Still, the study may have important clinical implications because African Americans are at particularly high risk for premature cardiovascular death, especially once they progress to CKD.

“With close follow-up care and excellent blood pressure control, we can have a significant impact in decreasing the rates of cardiovascular morbidity and mortality,” Dr. Alves told Renal & Urology News.

In addition, the new study may provide insight into the relationship between hypertension and renal disease in African Americans, as well as some of the reported racial differences in ESRD rates and outcomes, she said. “The study is timely given the increased recognition of medical health disparities observed among African American patients,” Dr. Alves said. “This type of information is needed if solutions are to be sought at the clinical and policy levels.”
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