What Hurts the Heart Also Hurts the Kidney
Study finds same factors increase risk for both diseases
TUESDAY, Feb. 17, 2004 (HealthDayNews) -- The same risk factors that lead to heart attack and stroke -- high blood pressure, smoking, obesity, diabetes and high cholesterol levels -- can also cause kidney failure, says the latest report from the long-running Framingham Heart Study.
"It's not necessarily a surprise," says Dr. Caroline S. Fox, lead author of the research, which appears in the Feb. 18 issue of the Journal of the American Medical Association. Vascular problems, the kind of damage to blood vessels that result in heart attack, stroke and other cardiovascular conditions, can also damage the kidneys, she says, although that is not a complete explanation of the relationship.
"Certainly the kidney is a vascular organ," says Fox, who is an epidemiologist at the Framingham study. "But it is more complex than that. We don't know the exact mechanism."
But the numbers showing the relationship are clear, she says. They come from data of 1,223 men and 1,362 women who had an initial medical examination between 1978 and 1982 and came back for a checkup an average of 18.5 years later.
Over that period, 224 of them developed kidney disease, defined as a substantial drop in the kidneys' ability to filter waste from the blood. Such a drop in what is formally called the glomerular filtration rate can lead to kidney failure that requires either dialysis treatment or a kidney transplant to keep the patient alive.
The relationship between cardiovascular risk factors and kidney disease was clear. Diabetes more than doubled the risk, high blood pressure increased it by more than 50 percent, smoking increased it by more than 40 percent, and obesity increased it by more than 20 percent.
A number of earlier studies have linked these individual factors to kidney disease, Fox says, "but before this they have not been studied together."
The results point the way to prevention. Because people who started with a below-average glomerular filtration rate were much more likely to develop kidney disease, their kidney function should be monitored regularly, Fox stresses.
There is a close relationship between kidney disease and cardiovascular diseases, she notes. Someone with kidney failure has a 10- or 20-fold higher risk of heart attack, stroke and other cardiovascular conditions than someone with normal kidney function.
The problem is widespread. An estimated 275,000 Americans have kidney failure, and perhaps 8 million have some form of kidney disease.
"This study re-emphasizes the importance of controlling the traditional risk factors in order to prevent not only heart attacks but also the development of kidney disease, stroke and heart failure," says Dr. Robert A. Phillips, chairman of medicine at Lenox Hill Hospital in New York City. "We need to redouble our efforts to control blood pressure and reduce smoking so that kidney disease does not get a chance to develop."
Get a primer on kidney disease from the National Institute of Diabetes and Digestive and Kidney Diseases, while the American Heart Association has a page on risk factors you can and can't control.