C-Reactive Protein, Interleukin-6, and Soluble Adhesion Molecules as Predictors of Progressive Peripheral Atherosclerosis in the General Population

Abstract

Background— The relationship between levels of circulating inflammatory markers and risk of progressive atherosclerosis is relatively undetermined. We therefore studied inflammatory markers as predictors of peripheral atherosclerotic progression, measured by the ankle-brachial index (ABI) at 3 consecutive time points over 12 years. Methods and Results— The Edinburgh Artery Study is a population cohort study of 1592 men and women aged 55 to 74 years. C-reactive protein (CRP), interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), and E-selectin were measured at baseline. Valid ABI measurements were obtained on 1582, 1081, and 813 participants at baseline and 5-year and 12-year follow-up examinations, respectively. At baseline, a significant trend was found between higher plasma levels of CRP ( P ≤0.05) and increasing severity of peripheral arterial disease (PAD), after adjustment for baseline cardiovascular risk factors. IL-6 at baseline ( P ≤0.001) was associated with progressive atherosclerosis at 5 years (ABI change from baseline), and CRP ( P ≤0.01), IL-6 ( P ≤0.001), and ICAM-1 ( P ≤0.01) were associated with changes at 12 years, independently of baseline ABI, cardiovascular risk factors, and baseline cardiovascular disease. Only IL-6 independently predicted ABI change at 5 years ( P ≤0.01) and 12 years ( P ≤0.05) in analyses of all inflammatory markers simultaneously and adjusted for baseline ABI, cardiovascular risk factors, and cardiovascular disease at baseline. Conclusions— These findings suggest that CRP, IL-6, and ICAM-1 are molecular markers associated with atherosclerosis and its progression. IL-6 showed more consistent results and stronger independent predictive value than other inflammatory markers.