Prevalence and Oucomes of Low Ankle Brachial Index in ASCVD Risk Categories-From the National Health and Nutrition Examination Survey

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Introduction: The utility of Ankle Brachial Index(ABI) as a risk-enhancer to the pooled cohort equations(PCE) in assessing cardiovascular risk for primary prevention of atherosclerotic cardiovascular disease(ASCVD) is uncertain. We aim to assess the prevalence and all-cause mortality of people with low ABI across ASCVD risk categories.

Hypothesis: Would the addition of ABI to standard ASCVD risk assessment improve all cause mortality risk stratification?

Methods: Participants were recruited as part of the National Health and Nutrition Examination Survey from 1999-2004 and mortality assessed on 12/31/2015. We included participants aged 40-75years with ABI values≤1.3 and data for ASCVD computation using the PCE. Persons with ABI

Results: The mean follow-up time was 156months(95%CI 154-158). Persons with low ABI were older(61 Vs 53years) and had higher mean systolic blood pressure(135 Vs 126mmHg). There was no difference in mean total cholesterol(mg/dl)[212(95%CI 210-214) vs. 208( 202-215)], LDL(mg/dl) [128 (95%CI 125-130) vs. 121(112-129)] and HDL(mg/dl) [54 (95%CI 53-54) vs. 52(50-55)] between the two ABI categories. The all-cause mortality was higher among persons with low ABI(43.1%) compared to those with normal ABI(12.2%), p

Conclusions: Approximately 67% of participants with low ABI were classified as low, borderline or intermediate risk by PCE. Low ABI was associated with increased all-cause mortality in the intermediate/borderline and high ASCVD risk categories but not in the low ASCVD risk category. Our study supports the use of ABI in risk stratification for primary prevention of ASCVD in individuals with borderline or intermediate risk.