Aortic stiffness: an age-related prognostic marker?

Aortic stiffness, a consequence of vascular aging, is an independent predictor of cardiovascular morbidity and mortality. However, the impact of age and sex on its predictive performance remains unclear. We have included 6046 individuals from the population-based Rotterdam study. Survival analyses were performed to investigate the impact of age and sex on the link between aortic stiffness and outcomes, including coronary heart disease (CHD), stroke, cardiovascular disease (CVD), cardiovascular and all-cause mortality. The added predictive value of aortic stiffness across age categories and by sex was assessed by using explained variation, Harrell's C index and Integrated Discrimination Improvement (IDI). Aortic stiffness was independently associated with all outcomes [hazard ratio (95% confidence interval; CI): 1.16 (1.04-1.22) for CHD, 1.09 (1.00-1.19) for stroke, 1.11 (1.05-1.18) for CVD, 1.14 (1.05-1.23) for cardiovascular mortality, 1.08 (1.03-1.13) for all-cause mortality]. The strength of the association between aortic stiffness and stroke, cardiovascular and all-cause mortality decreased significantly by advancing age. The variance of the outcome (R2) explained by aortic stiffness alone was noticeable in individuals younger than 60 years and negligible in the other age categories. The association of aortic stiffness and CHD was stronger in women than in men. Similarly, the difference in R2 between women and men was greater for CHD than for the other considered outcomes. Our findings suggest that the gain in explained variation caused by aortic stiffness for CVD and mortality might be limited to individuals younger than 60 years.