The problems often occur in patients with no known history of cardiovascular problems. And current approaches to figure out who is at risk, which look at things like smoking, blood pressure and cholesterol, give mixed results.

For the report, which appears in the July 9 issue of The Journal of the American Medical Association, researchers reviewed 16 studies that looked at the medical histories of more than 24,000 men and more than 23,000 women.

To establish an ankle brachial index, doctors look at the ratio between the systolic pressure at the ankle and at the arm. A lower index number, the study found, was a reliable indicator of cardiovascular risk.

The study suggested combining the index with other scales now used, like the Framingham risk score, to get a more accurate measure. When they did that for the study, the researchers found, about one man in five fell into a lower risk category, while a third of the women ended up in a higher one. This would suggest that some men may have been getting treatment they did not need, while some women were not getting treatment they should have.