Ankle-brachial index improves the classification of cardiovascular risk: PERART/ARTPER Study

The sensitivity of cardiovascular risk functions is low because many cardiovascular events occur in low- or intermediate-risk patients. The aim of the present study was to evaluate how the ankle-brachial index (ABI) reclassifies these patients.

We conducted a descriptive, transversal, multicenter study (28 centers) of 3171 randomly selected patients aged >49 years. We studied demographic variables, clinical history and cardiovascular risk factors, ABI (defined as pathologic if <0.9) and 10-year cardiovascular risk with the Framingham-Wilson, REGICOR and SCORE equations, dividing risk into three categories: low (Framingham<10%, REGICOR<5% and SCORE<2.5%, intermediate (10-19.9%, 5-9.9% and 2.5-4.9%, respectively) and high (≥20%, ≥10% and ≥5%, respectively). Low- or intermediate-risk patients were reclassified as high-risk if they presented ABI <0.9.

We compared patients with ABI <0.9 and patients with ABI ≥0.9 and found the former were significantly older, more frequently men, had a worse history and more cardiovascular risk factors, and included more high-risk patients than when the classification used Framingham-Wilson (42.7% vs. 18.5%), REGICOR (25.8% vs. 9.3%) and SCORE (42.2% vs. 15.9%) equations. In men, using ABI led to a 5.8% increase in the high-risk category versus Framingham-Wilson, a 19.1% increase versus REGICOR and a 4.4% increase versus SCORE. In women, the increases were 78.6% versus Framingham-Wilson, 151.6% versus REGICOR and 50.0% versus SCORE.

The ABI reclassifies a substantial proportion of patients towards the high-risk category. This is particularly marked in women and by comparison with REGICOR scores.