TUESDAY, July 8, 2008 (HealthDay News) -- A seldom-used test that measures blood pressure in the ankle and the arm can help improve assessment of the risk of heart disease, stroke and other cardiovascular problems, an international research group reports.
It has a distinct advantage in that it is extremely easy to perform and doesn't require expensive, sophisticated equipment, Gerry Fowkes, a professor of epidemiology at the University of Edinburgh, Scotland, said of the ankle brachial index (ABI). The device is the subject of a report in the July 9 issue of the Journal of the American Medical Association. The index is the ratio between the blood pressure measurements in the ankle and the arm.
The ABI should be used to supplement rather than replace standard measures of cardiovascular risk such as cholesterol, blood pressure, obesity and physical activity, Fowkes said.
"It has been shown that using these common risk factors, prediction is not as good as it might be," he said. "That is why we and others have been looking for other factors to improve prediction."
The meta-analysis used data from 16 studies around the world, including 24,955 men and 23,339 women who were followed after an initial ABI measurement. Over the next 10 years, 4.4 percent of men with a normal ABI died, compared to 18.7 percent of men with an abnormally low ABI. Death rates for women were 12.6 percent for those with a low ABI, 4.1 percent for those with a normal ABI.
A lower ABI was associated with approximately a doubled risk of death from any cause, cardiovascular death, and a major coronary event over the 10 years, the report said. Including the ABI in current risk factor assessments would mean reclassification of cardiovascular risk and change of the measures taken to prevent cardiovascular events for 19 percent of men and 36 percent of women, the researchers estimated.
Studies about the use of the ABI are continuing, Fowkes said. "The next step is to look at the prediction made by combining the ABI and other risk factors," he said. "Any individual who is having a cardiovascular risk assessment would benefit from having this test, but when we have done further work in looking at the detailed accuracy of the prediction, proper use of the test will become more obvious."
ABI testing right now isn't for everyone, said Dr. Aaron B. Folsom, a professor of epidemiology at the University of Minnesota, and a member of the research team.
It is being promoted as a way of measuring the risk of peripheral arterial disease (PAD), blockage of blood vessels in the legs, and so it is best used for older people, who are at greater risk of PAD, Folsom said. Wider use can be proposed, because "the more information you have, the better you do in classifying cardiovascular risk," Folsom said.
A low ABI reading would mean greater emphasis for that individual on the classic risk factors -- blood cholesterol, blood pressure, diabetes, obesity and the others, Folsom added. "We do have interventions that we know work, such as glucose-lowering and physical activity," he said.
Learn how the ABI is determined and what it means from the Vascular Disease Foundation.