Low ankle-brachial pressure index predicts increased risk of cardiovascular disease independent of the metabolic syndrome and conventional cardiovascular risk factors in the Edinburgh Artery Study

Abstract

Objective: To investigate whether a low ankle-brachial pressure index (ABI) predicts increased risk of cardiovascular disease (CVD) independent of the metabolic syndrome and conventional cardiovascular risk factors.

Research design and methods: The Edinburgh Artery Study is a population-based cohort study in which subjects were followed up until their death or for approximately 15 years. Low ABI at baseline was defined as <0.9; subjects with ABI >1.4 (n = 13) were excluded from the analyses. We used a modified version of the definition of the metabolic syndrome published in the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults, replacing waist circumference criteria with BMI criteria. Data on relevant parameters were available for 1,467 men and women ages 55-74 years at baseline. Cox proportional hazards models were used to study cardiovascular morbidity and mortality before and after adjusting for potential confounding factors.

Results: We determined that 25% of the study population had the metabolic syndrome and that a low ABI was more prevalent among people with than without the metabolic syndrome (24 vs. 15%; P < 0.001). During the follow-up period, there were 226 deaths from CVD and 462 nonfatal cardiovascular events. The hazard ratio (95% CI) for low ABI after adjusting for age, sex, baseline CVD, diabetes, smoking status, LDL cholesterol, and metabolic syndrome was 1.5 (1.1-2.1) for CVD mortality and 1.5 (1.2-1.8) for all CVD outcomes.

Conclusions: Low ABI is associated with increased risk of CVD independent of the metabolic syndrome and other major CVD risk factors.