Chicago, IL - Ankle brachial index (ABI) and leg symptoms can be used to identify high-risk peripheral arterial disease (PAD) patients, researchers say. The study, appearing in the July 28, 2004 issue of the Journal of the American Medical Association, challenges standard thinking about the natural history of leg functioning in PAD patients.1 Stable or improved claudication symptoms have traditionally been considered signs of slowing disease progression, but this work casts doubt on that assumption, contending that it may actually flag alarming reductions in levels of physical activity.

Clinicians should consider patients with PAD at increased risk of functional decline.

Lead investigator Dr Mary McGrae McDermott (Northwestern University Feinberg School of Medicine, Chicago, IL) and her team found that PAD is associated with a significant decline in walking endurance over a two-year follow-up. They identified that an ankle brachial index of less than 0.50, leg pain on exertion and rest, and asymptomatic PAD are all associated with greater functional decline.

"Our findings are particularly important given the high prevalence of undiagnosed and asymptomatic PAD," McDermott told heartwire. "Clinicians should consider patients with PAD at increased risk of functional decline compared with those without PAD."

In this prospective cohort study, McDermott and colleagues looked at 676 consecutively identified individuals age 55 years or older with and without PAD (417 and 259). PAD was defined as an ankle brachial index of less than 0.90, and participants with PAD were categorized at baseline into one of five mutually exclusive symptom groups.

The researchers found that lower baseline ankle-brachial-index values were associated with a greater decline in walking endurance. Participants with ABIs of less than 0.50 at baseline had a nearly 13-fold increased risk of becoming unable to walk continuously for six minutes two years later, compared with participants with ABIs of 1.10 to 1.50.

McDermott and colleagues found that baseline leg symptoms among participants with PAD also predicted rates of functional decline. Participants with PAD having leg pain on exertion and rest experienced greater declines in walking endurance and walking speed than did individuals without PAD.

The researchers also found that compared with participants without PAD, asymptomatic PAD was associated with greater decline in walking endurance and an increased odds ratio for becoming unable to walk continuously for six minutes (3.63 [95% CI 1.58-8.36], p=0.002).

"Our findings underscore the importance of using the ABI to identify persons with PAD since PAD is frequently undiagnosed or symptomatic," McDermott and colleagues write. "Further study is necessary to develop treatments to prevent functional decline in patients with PAD who do not have classic intermittent claudication."