Prevalence of abnormal ankle-brachial index among individuals with low or intermediate Framingham Risk Scores.

PURPOSE: To determine the prevalence of an abnormal ankle-brachial index (ABI) among subjects not considered to be at high risk for cardiovascular disease (CVD) based on the Framingham Risk Score (FRS).

MATERIALS AND METHODS: Data from the Population-Based Examinations to Determine Ankle-brachiaL index (PEDAL) Study (2007-2009), a cross-sectional study at 23 U.S. sites, in conjunction with Legs for Life, a national ABI screening program, were analyzed. This study includes data from 822 participants (average age 64.3 years ± 11.6, 69.7% women, 89.7% non-Hispanic white) without known CVD or diabetes, who were screened for peripheral artery disease (PAD) with an ABI and for whom all FRS variables were available. Participants' 10-year coronary heart disease (CHD) risk was estimated from the FRS, and three risk categories were defined: low (< 10%), intermediate (10%-19%), and high (≥ 20%). ABI < 0.90 or > 1.4 in either leg was considered abnormal.

RESULTS: The prevalence of abnormal ABI was 14.2% (95%confidence interval [CI] 11.9%-16.8%). According to the FRS, 463 (56.3%) participants were at low risk, 212 (25.8%) were at intermediate risk, and 147 (17.9%) were at high risk. Among participants with a low FRS (n = 463; without CVD or diabetes or both) and an intermediate FRS (n = 212; without CVD or diabetes or both), 12.3% and 12.2% had an abnormal ABI.

CONCLUSIONS: The prevalence of abnormal ABI, a CHD equivalent, is high among individuals not identified as high risk by conventional Framingham-based risk assessment.