Prevalence and outcomes of low ankle brachial index by atherosclerotic cardiovascular disease risk level: Insights from the National Health and Nutrition Examination Survey (NHANES)

Introduction

Cardiovascular disease is the leading cause of mortality in the US.

Primary prevention begins with the assessment of ASCVD risk. All risk estimation tools have inherent limitations, and population-based risk equations must be interpreted in light of specific circumstances for individual patients. Use of the sex- and race-specific pooled cohort equations (PCE) to assess the 10-year risk of a first ASCVD event is recommended as an initial step in risk assessment for adults aged 40–79 years of age and in identifying individuals eligible for primary prevention therapies. The PCE have been shown to overestimate or underestimate ASCVD risk for certain subgroups. Thus, after calculation of the PCE, it is recommended to use additional risk-enhancing factors to guide shared decision making about preventive interventions, particularly for borderline- or intermediate-risk adults, one of which is the ankle brachial index (ABI). Low ABI (< 0.9) has been associated with cardiovascular events and mortality and can be helpful for shared decision making regarding initiation of statin therapy. However, there are no data on the prevalence of low ABI among individuals with ASCVD in the borderline or intermediate risk categories. Furthermore, no data exist regarding mortality differences between normal and low ABI groups among individuals in the borderline and intermediate ASCVD risk categories. To address this gap in the literature, we set out to assess the prevalence of low ABI and all-cause mortality in persons with low, borderline and intermediate ASCVD risk using data collected from the National Health and Nutrition Examination Survey (NHANES) linked to mortality data.