The effect of aging on the association between coronary heart disease risk factors and carotid intima media thickness: An analysis of the Atherosclerosis Risk in Communities (ARIC) cohort

Objective: Aging decreases the strength of association between established coronary heart disease (CHD) and its risk factors. Carotid intima media thickness (IMT) is a widely used surrogate for coronary artery disease, which we hypothesized has a similar diminishing age-mediated strength of association with CHD occurrence and prevalence of its risk factors. Methods and results: Data from the Atherosclerosis Risk in Communities (ARIC) cohort of 14,562 individuals aged 45 to 64 (mean follow up nine years) was stratified into two age groups, 45-54 and 55-64 years, within each of ARIC's four examination visits (n=14,562; 13,622; 7869; 6628 for visits 1 to 4, respectively). Cross-sectional and longitudinal analyses with multiple linear and logistic regression modeling were used to compare the relationships between carotid IMT (the mean of six far wall sites from the right and left carotid bifurcation, common and internal carotid arteries with imputation of missing data) and the risk factors of smoking, hypertension, hypercholesterolemia, diabetes, and obesity with age. The strength of the associations between carotid IMT and most risk factors were qualitatively stronger across successive visits and within each visit, these associations were stronger in the older, as compared to the younger, age group. Conclusions: In a large cohort followed for nearly one decade, our hypothesis that age attenuates the association of CHD risk factors and carotid IMT was not supported by ARIC data. Rather, we found that associations between carotid IMT and CHD risk factors remained stable with advancing age, contrary to the relationship between risk factors and CHD outcomes with age. These findings suggest that there is efficacy to continued risk factor management in the elderly.