Kidney Disease Substantially Worsens in a
Fourth of African Americans despite Therapy for Hypertension
The best available treatment for chronic kidney disease from high
blood pressure did not keep the disease from substantially worsening
in about a fourth of African-Americans studied, according to long-term
results of a National Institutes of Health study published April
28, 2008, in the Archives of Internal Medicine.
The largest and longest study of chronic kidney disease in African-Americans — the
African American Study of Kidney Disease and Hypertension (AASK) — found
that the disease substantially worsened in about one-fourth of
participants, even with very good blood pressure control and use
of kidney-protecting medications, currently the best available
treatment. This subgroup of patients either lost half their kidney
function or reached kidney failure, also known as end-stage renal
"Despite these sobering results, blood pressure control is
still vital in kidney disease and in many other diseases," said
NIH Director Elias A. 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."
Good news also emerged from the study. About one-third of participants
experienced a slow decline in kidney function, about what is generally
observed with aging. "The factors that may be responsible
for such a small loss of kidney function need to be studied," said
Lawrence Y. Agodoa, M.D., senior author of the study and director
of kidney failure research at NIH’s National Institute of Diabetes
and Digestive and Kidney Diseases (NIDDK), which funded the study.
The AASK Cohort Study observed about 750 African-Americans on
recommended therapy for chronic kidney disease from 2002 to 2007.
Study participants were initially recruited beginning in 1995 for
the AASK Clinical Trial www.nih.gov/news/pr/nov2002/niddk-25.htm,
which concluded in 2001 that an ACE inhibitor medication protected
the kidneys better than two other classes of blood pressure drugs.
During the Cohort Study, nearly 9 out of 10 participants were taking
an ACE inhibitor or an angiotensin receptor blocking drug, and
average blood pressure was 133/78 mmHg, close to national guidelines
for high blood pressure in people with chronic kidney disease.
Uncontrolled high blood pressure, an increase in the number of
people with diabetes, and the aging of the U.S. population means
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 chronic kidney disease. And 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
Diabetes and high blood pressure are leading causes of kidney
disease, which runs in families and disproportionately affects
African-Americans and American Indians. The condition can lead
to kidney failure, premature death, heart attacks, strokes, bone
disease, and growth and developmental problems in children. Blood
and urine tests are the only way to find kidney disease early,
when treatment is more likely to significantly delay or prevent
kidney failure. Important therapies that help protect the kidneys
include careful control of high blood pressure — and blood
sugar in people with diabetes — ACE (angiotensin-converting
enzyme) inhibitors or ARBs (angiotensin receptor blockers) to reduce
protein in the urine, and therapies to reduce the risk of cardiovascular
disease, which increases the risk of developing kidney disease.
Learn more about early detection and treatment from NIDDK’s National
Kidney Disease Education Program at www.nkdep.nih.gov or by calling
toll-free 1-866-4-KIDNEY (1-866-454-3639).
The AASK Trial and Cohort Study were conducted at 21 U.S. medical
centers and have been funded by NIDDK since 1994. Additional support
was provided by NIH’s National Center on Minority Health and Health
Disparities and by King Pharmaceuticals.
The National Institute of Diabetes and Digestive and Kidney Diseases,
a component of the NIH, conducts and supports research in diabetes
and other endocrine and metabolic diseases; digestive diseases,
nutrition, and obesity; and kidney, urologic, and hematologic diseases.
Spanning the full spectrum of medicine and afflicting people of
all ages and ethnic groups, these diseases encompass some of the
most common, severe, and disabling conditions affecting Americans.
For more information about NIDDK and its programs, see www.niddk.nih.gov.
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.