TUESDAY, July 27, 2004 (HealthDayNews) -- A test that checks blood pressure in the ankle as well as the arm can warn of a future loss of mobility caused by blockage of the leg arteries, even if that blockage is causing no obvious problems, a study finds.
The test measures the ankle brachial index (ABI), the ankle blood pressure divided by the blood pressure in the arm. A normal ABI is between 1.0 and 1.1, with lower readings indicating reduced blood flow in the legs caused by narrowing of the arteries.
The study of nearly 700 people aged 55 and older found those with low ABI readings had significant declines in walking endurance over the next two years compared to those with normal readings, even when the artery blockage was causing no apparent symptoms. The report, by researchers at the Northwestern University Feinberg School of Medicine, appears in the July 28 issue of the Journal of the American Medical Association.
Participants with ABIs below 0.5 were nearly 13 times more likely to be unable to walk for six straight minutes than those with normal readings, the study found.
The most significant finding was that the loss of mobility occurred in people who were not experiencing intermittent claudication, the leg pain that is the classic symptom of what is formally called peripheral arterial disease (PAD), said study leader Dr. Mary McGrae McDermott, an associate professor of medicine at Northwestern.
As expected, the people with PAD whose legs hurt them after they walked for a while did have a greater reduction in walking endurance than people without PAD. But the study also found patients whose PAD was causing no symptoms "had significantly greater declines in six-minute walk performance than did participants without PAD."
That finding suggests the need to screen everyone aged 70 and older for PAD, and to do that screening starting at age 59 for smokers and people with diabetes, who are at increased risk of leg artery blockage, McDermott said. The reason is that early detection and treatment can often help people stay on their feet longer.
The basic treatment is simple, McDermott said: walking, preferably in a controlled situation.
"Supervised treadmill walking appears to be the best, with a nurse or physiologist present, for 30 minutes three times a week," she said, acknowledging that "even if you walk at home, you can get some benefit."
It has been thought that people with symptom-free PAD did not suffer any deterioration in walking endurance, McDermott said. It now appears that those people were reporting no trouble simply because their condition caused them to walk less, she said.
"When you walk slower, you don't feel pain, but you decrease your functional capacity," said Dr. Richard A. Stein, associate chairman of medicine at Beth Israel Medical Center in New York City and a spokesman for the American Heart Association.
Treatment for PAD, even if it causes no symptoms, is helpful for more than just walking, McDermott said. The condition is associated with an increased risk of heart attack, stroke and other cardiovascular problems.
It is important to detect those patients because PAD, like any other artery-blocking condition, will progress steadily unless treated, possibly leading to gangrene that requires amputation, Stein said.
An essential treatment is "vigorous, vigorous" control of risk factors such as blood cholesterol level and smoking, Stein said. But doctors are starting to use some of the same techniques employed for blockage of heart arteries, such as implanting stents, flexible tubes that keep blood flowing, Stein added.
Read about peripheral arterial disease at the American Heart Association.