The six-minute walk test, a simple, inexpensive diagnostic test, can reliably predict risk of death or re-hospitalization in African-American patients with heart failure, according to a study by a cardiologist now at the University of Illinois at Chicago College of Medicine.
"The six-minute walk test is basically just what it sounds like," said Dr. Thomas Stamos, assistant professor of cardiology at UIC and principal investigator of the study.
In the study, which was conducted at was conducted at the John H. Stroger, Jr. Hospital of Cook County, 200 African-American patients, 125 men and 75 women, who were admitted to the hospital with decompensated heart failure (patients whose heart failure has caused their lungs to fill with fluid and who may have fluid in their legs) were asked to walk for six minutes, usually just up and down a hospital corridor. The distance that they are able to walk was then measured.
The six-minute walk test has been successful in previous studies in predicting the course of heart failure. But the usual cause of heart failure in African-Americans patients is hypertension rather than the cardiovascular disease seen in the white patient population, says Stamos, and African-Americans often respond differently to medications used to treat heart failure.
"There was a possibility that African Americans would have a different response to the six-minute walk test," said Stamos. "It was important to prove that this test could reliably predict outcomes in this patient population."
The researchers found "a clear difference" between patients who could walk at least 200 meters in six minutes and those who couldn't, Stamos said. Patients who walked 200 or more meters -- about twice the length of a football field -- had substantially lower risk of either returning to the hospital or dying during the course of the study.
"We hope this study can help us decide which patients we should concentrate our efforts on," said Stamos. "If we know that a patient is at very high risk, we may be more aggressive with their medical therapy, we may have them follow-up in the clinic more frequently and keep a closer eye on them in order to prevent these negative outcomes."
The patients were followed for 40 months to see how frequently they were forced to return to the hospital with heart failure as well as what percentage died during the course of the study.
The researchers found that 40 percent of patients who were only able to walk less than 200 meters died in the 40 months following their original hospitalization versus only 19 percent of the patients who were able to walk more than 200 meters.
Patients were also re-hospitalized more often if they were unable to walk more than 200 meters. About 70 percent of the patients who were unable to walk more than 200 meters were re-hospitalized during that 40 month time period versus 52 percent of the patients who were able to walk farther.
"With this very simple test, we were have a very powerful tool for predicting both who is at highest risk of dying in this period of time, as well as who would be re-hospitalized with heart failure, giving us a chance to plan appropriate treatment," Stamos said.
Other contributors on the study are Dr. M. Tarek Alahdab of UIC, Dr. Ibrahim N. Mansour of Stroger Hospital, and Dr. Sirskarn Napan of the Southern Illinois University School of Medicine at Springfield. The study was published in the March issue of the Journal of Cardiac Failure.
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