Contribution of the ankle-brachial index to improve the prediction of coronary risk: The ARTPER cohort

Background The different cardiovascular risk prediction scales currently available are not sufficiently sensitive. Aim The aim of the present study was to analyze the contribution of the ankle-brachial index (ABI) added to the Framingham and REGICOR risk scales for the reclassification of cardiovascular risk after a 9-year follow up of a Mediterranean population with low cardiovascular risk. Design and setting A population-based prospective cohort study was performed in the province of Barcelona, Spain. Method A total of 3,786 subjects >49 years were recruited from 2006-2008. Baseline ABI was performed and cardiovascular risk was calculated with the Framingham and REGICOR scales. The participants were followed until November 2016 by telephone and review of the clinical history every 6 months to confirm the possible appearance of cardiovascular events. Results 2,716 individuals participated in the study. There were 126 incidental cases of first coronary events (5%) during follow up. The incidence of coronary events in patients with ABI <0.9 was 4-fold greater than that of subjects with a normal ABI (17.2/1,000 persons-year versus 4.8/1,000 persons-year). Improvement in the predictive capacity of REGICOR scale was observed on including ABI in the model, obtaining a net reclassification improvement of 7% (95% confidence interval 0%-13%) for REGICOR+ ABI. Framingham + ABI obtained a NRI of 4% (-2%-11%). Conclusion The results of the present study support the addition of the ABI as a tool to help in the reclassification of cardiovascular risk and to confirm the greater incidence of coronary events in patients with ABI < 0.9.