Objective: Beyond the use of exercise ankle-brachial index (ABI) to diagnose peripheral artery disease (PAD), an exercise ABI can provide further insight into the functional significance of PAD. While ACC/AHA guidelines recommend exercise ABI only when resting measurement is normal and symptoms are suggestive of PAD, the variability in the use of exercise ABI, patient’s factors associated with its use and its relation to patient’s symptoms as quantified by the Peripheral Artery Questionnaire (PAQ), are unknown.
Methods: From the multinational PORTRAIT registry, between 06/2011 and 02/2015, we identified 1,132 consecutive patients with PAD (resting ABI ≤ 0.9). We built a hierarchical logistic regression model, including random effects for site and country, to examine predictors and variation, by the calculation of fully-adjusted median odds ratios (MOR), in ordering exercise ABIs. Lastly, association between exercise ABI (absolute and relative change in ABI with exercise, pain-free walking distance (PFWD), and maximum walking distance (MWD)) and PAQ (physical limitation, symptoms and summary) scores were studied using Spearman’s correlation.
Results: Exercise ABI was ordered in 572 (51%), 33% in USA vs. 67% in Europe/ Australia. Exercise ABI testing was more likely to be performed if patient was male and younger, and when typical symptoms and most importantly less severe resting ABI were present. Substantial variability across sites after adjusting for patient factors was observed, with a MOR of 57.1 (95% CI: 6.2 - 524) between the US and other countries and of 5.9 (95% CI: 3.2 - 19.5) among sites. More importantly, PFWD and MWD correlated with PAQ scores and particularly physical limitation scores (rs = 0.38, P < 0.001 and rs = 0.37, P < 0.001, respectively). Remarkably, there appears to be a plateau point at about 180-200 m for PFWD and at about 300-350 m for MWD, below which PAQ scores drop steeply, particularly physical limitation scores.
Conclusions: Exercise ABI use is remarkably variable. Its data, specifically PFWD and MWD, might be helpful in objectively assessing quality of life in patients with PAD; however, better objective assessment tools are still needed to establish a baseline and enable accurate objective assessment at follow-ups.