Predictors of Change in the Ankle Brachial Index with Exercise

A 20% or greater decrease in the ankle brachial index (ABI) with exercise is suggestive of peripheral artery disease (PAD), and could identify patients with an increased mortality risk. The predictors of a change in the ABI with exercise have received little attention.

This was a cross-sectional analysis. Two hundred and sixty five participants of the San Diego Population Study with a resting ABI between 0.90 and 1.10 performed 50 heel raises and immediately had their ABIs measured again. The relationship between the change in the ABI with exercise and multiple potential risk prediction variables were examined using linear regression. In addition, the categorical percent change in the ABI with exercise was analysed by multinomial logistic regression.

The mean age of participants was 71.8 years, and 80.4% were female. At rest, the average ABI was 1.04 (SD 0.04) before and 0.94 (SD 0.13) after exercise; a mean decrease of 9.5%. In analyses of ABI change as a continuous variable, higher age, any smoking history, and a diagnosis of chronic obstructive pulmonary disease (COPD) were associated with a significant decrease in the ABI with exercise (p = .01, .04, and .03, respectively). Categorical analyses of the risk factors associated with a 20% or greater ABI decrease with exercise confirmed these results. Congestive heart failure was associated with an increased ABI with exercise (p = .04) in continuous ABI change analyses only.

Older age, a positive history of smoking, and a history of COPD were independently and significantly associated with a greater ABI decrease with exercise. These risk variables may help identify persons with subclinical PAD.