One-third of African-Americans with chronic kidney disease may benefit from lower blood pressure goals

WORCESTER, Mass. — African-Americans suffering from chronic kidney disease (CKD) who show evidence of protein in their urine may benefit from a lower blood pressure standard, according to a study by the African-American Study of Kidney Disease and Hypertension (AASK), a consortium of 22 medical centers in the United Sates including clinical scientists at the University of Massachusetts Medical School and UMass Memorial Medical Center. The study, funded by the National Institutes of Health, appears in the Sept. 2 issue of the New England Journal of Medicine.

The AASK study found that among African-Americans with protein in their urine, setting a blood pressure goal at a lower level, roughly 130/80 mmHg instead of the standard 140/90 mmHg, reduced the likelihood of kidney disease progression, kidney failure or death by 27 percent. High blood pressure can damage blood vessels throughout the body and, if blood vessels in the kidney are affected, the kidneys may stop removing excess waste and fluid from the body, resulting in protein in the urine. Experts estimated that 33 percent of patients with chronic kidney disease have enough protein in their urine that they would benefit from maintaining a lower blood pressure. In patients without elevated protein levels, a lower blood pressure goal was no better at slowing progression of kidney disease than a standard blood pressure goal.

“Chronic kidney disease is a major and growing public health problem,” said Robert A. Phillips, MD, PhD, professor of medicine at the University of Massachusetts Medical School and director of the Heart and Vascular Center of Excellence at UMass Memorial Medical Center. “Rigorous, long-term studies, such as the AASK, provide new insights into the treatment of diseases that progress over years and which would otherwise be impossible to identify. In this study, we learned that a more intensive blood pressure control may be an important approach to preventing kidney disease progression.”

This information may encourage physicians treating patients with CKD to use evidence-based, personalized medicine, allowing them to tailor a treatment regiment to each patient’s unique characteristics. “AASK provides the strongest evidence to date that a lower blood pressure goal may be beneficial, in terms of preventing kidney disease progression,” said Phillips, who is also director of the Cardiovascular Core Laboratories for the AASK and is a member of the study’s executive committee. “Physicians treating African-Americans with chronic kidney disease should monitor their patients’ urine for protein and consider a lower blood pressure goal.”

In the United States, roughly one-third of end-stage kidney disease cases are attributed to hypertension or high blood pressure, which costs $35 billion annually in health care. The burden of kidney disease is especially high in African-Americans, who constitute only 12 percent of the population, but 32 percent of patients with end-stage kidney disease.

ASSK is the largest and longest study of kidney disease in African-Americans, following 1,094 study participants for approximately 12 years. The study was conducted in two phases: First, in a clinical trial from 1995 to 2001, participants were randomly assigned to a standard blood pressure goal (140/90 mmHg) or a lower goal (less than 130/80 mmHg). After the conclusion of that study, AASK participants who had not yet developed end-stage renal disease were invited to participate in the AASK follow-up study, which started in 2002.

In the follow-up study, all participants were given a blood pressure goal lower than 130/80 mm/Hg. Recommended blood pressure therapy started with an angiotensin converting enzyme (ACE) inhibitor, a widely used medication that works by inhibiting the production of the protein angiotensin II, which raises blood pressure. If blood pressure was not controlled, additional drugs were prescribed. On average, patients needed about 3.5 medications each day to control blood pressure. Millions of Americans take the drugs used in this study or similar drugs to treat health problems such as high blood pressure or heart disease.

The AASK trial and the follow-up study were conducted at 22 U.S. medical centers and were funded by the National Center on Minority Health and Health Disparities beginning in 1994. Additional support was provided by the NIH’s National Institute on Minority Health and Health Disparities, King Pharmaceuticals and other pharmaceutical companies that donated study drugs.

About the University of Massachusetts Medical School
The University of Massachusetts Medical School, one of the fastest growing academic health centers in the country, has built a reputation as a world-class research institution, consistently producing noteworthy advances in clinical and basic research. The Medical School attracts more than $240 million in research funding annually, 80 percent of which comes from federal funding sources. The mission of the Medical School is to advance the health and well-being of the people of the commonwealth and the world through pioneering education, research, public service and health care delivery with its clinical partner, UMass Memorial Health Care. For more information, visit www.umassmed.edu

About the National Institute of Diabetes and Digestive and Kidney Diseases
The NIDDK, part of the NIH, conducts and supports basic and clinical research and research training on some of the most common, severe and disabling conditions affecting Americans. The Institute's research interests include diabetes and other endocrine and metabolic diseases; digestive diseases, nutrition and obesity; and kidney, urologic and hematologic diseases. 

About the National Center on Minority Health and Health Disparities
The NIMHD (formerly NCMHD) promotes minority health and leads, coordinates, supports, and assesses the NIH effort to reduce and ultimately eliminate health disparities. NIMHD conducts and supports basic, clinical, social, and behavioral research, promotes research infrastructure and training, fosters emerging programs, disseminates information, and reaches out to minority and other health disparity communities. Visit

About the National Institutes of Health
The National Institutes of Health (NIH) — The Nation's Medical Research Agency — includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical, and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov