New statement says people with kidney disease are at highest risk for heart disease

American Heart Association
Tuesday, 28 October 2003

People with chronic kidney disease (CKD), even those in the early stages of the disorder, are in the highest-risk group for cardiovascular disease, the American Heart Association said in a statement in today's Circulation: Journal of the American Heart Association.

Kidney specialists have known that patients treated with dialysis for late stage kidney disease have a 10- to 30-fold greater risk than the general population of dying of cardiovascular events such as a heart attack or heart failure.

CKD is defined as kidney damage lasting more than three months that is confirmed by a biopsy or by "markers" of the disease. These markers include protein in the urine, abnormal urinary sediment, abnormal imaging studies, and/or a significant decrease in the rate at which the kidneys filter the blood.

These findings, which are often associated with untreated high blood pressure and/or diabetes, put a person at risk of heart problems, said Mark J. Sarnak, M.D., an assistant professor of medicine at Tufts-New England Medical Center in Boston.

"What we have recognized in recent years is that patients with any form of chronic kidney disease are also at high risk of cardiovascular events," said Sarnak, the lead author and co-chair of the expert panel that prepared the statement issued by the American Heart Association's Councils on the Kidney in Cardiovascular Disease, High Blood Pressure Research, Clinical Cardiology, and Epidemiology and Prevention.

The AHA statement supports the National Kidney Foundation's guidelines for treating CKD to prevent cardiovascular disease. It urges all panels that provide recommendations on treating and preventing heart disease to realize that patients with CKD are at high risk for heart disease.

"There are a lot of people with chronic kidney disease, and it is increasing," Sarnak said. "As the population ages, there will be more diabetes and more kidney disease."

The two most common causes of CKD are high blood pressure and diabetes, which are also risk factors for cardiovascular disease. Other causes include infections, genetic diseases and adverse drug reactions.

Traditional heart disease risk factors such as age, high cholesterol, high blood pressure, smoking and diabetes, increase heart disease risk for those with CKD. But CKD appears to carry its own non-traditional cardiac risk factors as well, which include anemia, malnutrition, inflammation and calcium and phosphorous abnormalities in the blood, Sarnak said.

Detecting CKD early requires both a blood and a urine test. "Unfortunately, it may be completely asymptomatic," he said.

So the American Heart Association statement urges physicians to periodically test the kidney function of people with certain conditions, including hypertension, diabetes and existing heart disease. Catching CKD early and treating it can delay, and perhaps prevent, adverse cardiovascular effects. Moreover, determining the cause of the disease will determine the best treatment regimen to cure or manage it.

"There are some very good treatments for kidney disease, and fortunately, there isn't a medication that is good for the kidney that is bad for the heart," Dr. Sarnak said.

Aggressive management of CKD patients includes keeping a patient's LDL cholesterol count below 100, controlling hypertension, and monitoring and treating the disease's secondary effects, such as calcium and phosphorous abnormalities, Sarnak said.

The statement makes several key points about CKD and heart risk:

• CKD is a worldwide problem, and patients with it are more likely to die of cardiovascular disease than to develop kidney failure.


• About 20 million Americans, or 10.8 percent of the U.S. population, have early CKD, and that number continues to rise. The number of CKD patients who need dialysis or a kidney transplant is expected to surpass 650,000 annually by 2010.


• Evidence suggests that small amounts of protein in the urine, a marker of kidney disease, increase heart disease risk in people with and without diabetes.


• CKD patients have several unique risk factors (anemia, malnutrition, inflammation and calcium and phosphorous abnormalities in the blood).


• Identifying CKD early may reduce cardiac events or death.


• CKD patients require aggressive treatment of heart disease risk factors.

The statement urged expanded research to resolve many issues that remain regarding the link between CKD and cardiovascular disease. For example, are the nontraditional risk factors, at all stages of the disease, also heart disease risk factors? Does CKD create a greater risk of heart failure or coronary disease? At what point does reduced kidney filtering increase heart disease risk? Will treatment focused on reducing urine protein decrease cardiovascular events?

"We are data limited; there is no question about it," Sarnak said. "Expanding the research effort could save many lives."

Andrew Levey, M.D., of Tufts-University School of Medicine, and Anton C. Schoolwerth, M.D., of Dartmouth Medical School in Hanover, New Hampshire also co-chaired the committee. Other co-authors are Josef Coresh, M.D, PhD.; Bruce Culleton, M.D.; L. Lee Hamm, M.D.; Peter A. McCullough, M.D., MPH; Bertram L. Kasiske, M.D.; Ellie Kelepouris, M.D.; Michael J. Klag, M.D., MPH; Patrick Parfrey, M.D.; Marc Pfeffer, M.D., PhD; Leopoldo Raij, M.D.; David J. Spinosa, M.D. and Peter W. Wilson, M.D.

For more information, or to contact American Heart Association, see their website at: www.americanheart.org