Kidney Disease Research Updates
Spring/Summer 2008

Research News

Kidney Disease Worsens Substantially in Some African Americans Despite Hypertension Therapy

The largest and longest study of chronic kidney disease (CKD) in African Americans found that the disease worsened substantially in about 25 percent of participants, despite very good blood pressure control and the use of kidney-protecting medications. Participants lost either 50 percent of their kidney function or reached kidney failure, according to the National Institutes of Health (NIH) study, which was published in the April 28, 2008, Archives of Internal Medicine.

The study also found that about one-third of the participants experienced a slow decline in kidney function—about what is generally observed with aging.

The African American Study of Kidney Disease and Hypertension (AASK) observed about 750 African Americans on recommended therapy for CKD from 2002 to 2007. Participants for this cohort study were initially recruited in 1995 for the AASK Clinical Trial, which found in 2001 that an angiotensin-converting enzyme (ACE) inhibitor medication protected the kidneys better than two other classes of blood pressure drugs. During the cohort study, nearly nine out of 10 participants were taking an ACE inhibitor or an angiotensin receptor blocking drug, and average blood pressure was close to the national guidelines for high blood pressure in people with CKD.

“Despite these sobering results, blood pressure control is still vital in kidney disease and in many other diseases,” said NIH Director Elias Zerhouni, M.D. “But this research clearly signals the importance of preventing kidney disease, better understanding causes, and finding better ways to manage it in the 26 million Americans who already have it.”

Uncontrolled high blood pressure, an increase in the number of people with diabetes, and the aging of the U.S. population mean more people than ever are getting and living with kidney problems. About 13 percent of the U.S. population, up from 10 percent in 1994, now have CKD. In 2005, more than 485,000 people were on chronic dialysis or had a kidney transplant for kidney failure, costing Medicare, private insurers, and patients $32 billion.

The AASK Clinical Trial and AASK cohort study were conducted at 21 U.S. medical centers and funded by the National Institute of Diabetes and Digestive and Kidney Diseases since 1994. Additional support was provided by the NIH National Center on Minority Health and Health Disparities and by King Pharmaceuticals.

For more information about kidney disease, visit the National Kidney and Urologic Diseases Information Clearinghouse at www.kidney.niddk.nih.gov.

NIH Publication No. 08–4531
July 2008

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