Modified Ankle–brachial Index Detects More Patients at Risk in a Finnish Primary Health Care

Abstract

Objectives Despite peripheral arterial disease (PAD), defined as ankle–brachial index (ABI) ≤ 0.9, being an independent predictor of cardiovascular morbidity and mortality, it is rarely used in the primary care. Various definitions for PAD (i.e., ABI ≤ 0.9 or ABI ≤ 0.95) exist. In addition, a modified ABI (ABI mod) using the lowest ankle pressure improves identification of patients at risk. The prevalence of PAD in primary care and association of different ABI calculations with atherosclerotic disease burden is not known. Design The research was conducted as a prospective cross-sectional study. Finnish health centres and 99 general practitioners were selected and trained for ABI measurement. Consecutive patients were recruited using inclusion criteria: age 50–69 years and one or more cardiovascular risk factors or age ≥70 years or calf pain during exercise. A total of 817 patients were recruited. Methods Research methods included interview and Doppler measurement of brachial and ankle pressures. Results An ABI mod ≤ 0.9 yielded the highest prevalence of PAD (47.7%), had the best sensitivity and identified the highest number of patients with coronary artery disease (CAD), cerebrovascular disease (CVD), PAD, CAD/CVD/PAD and polyvascular disease (PVD) at the cost of reduced specificity. All ABI calculations were independently associated with atherosclerotic disease burden. Interestingly, ABI ≥ 1.4 had the strongest association with CVD. Conclusions PAD is highly prevalent among patients presenting to primary care. ABI mod calculation detects more number of patients at risk at the cost of reduced specificity. The association of high ABI with CVD noted in this study warrants future research for validation.