Tobacco smoke and atherosclerosis: gender specific differences

Background. The harmful effect of smoking on atherosclerosis and cardiovascular health is well established. Educational and informational campaigns have been successful in reducing the number of smokers in men but not in women, where the number of smokers (initially less than men) is even increasing. We investigated the gender differences in the association of tobacco smoke with subclinical atherosclerosis and atherosclerosis progression taking into account the effects of other variables strongly associated with tobacco smoke: C reactive protein (CRP) and number of white blood cells (WBC) as inflammation markers, and education as an index of social class. Methods. The IMPROVE Study cohort includes 1694 men and 1893 women (age 54-79 years) at high risk of cardiovascular disease of five European countries. Baseline mean and maximum IMT of the left and right common carotids, bifurcations and internal carotid arteries and the fastest IMT-progression (15 months of follow up) detected in the whole carotid tree regardless of its location were computed. The chronic exposure to tobacco was assessed using a lifelong index of exposure (pack-year: cigarettes/day x smoke duration/20) and the acute exposure using an index of daily dose (cigarettes/day). Associations were assessed by multivariable analysis adjusting for conventional cardiovascular risk factors and recruiting centre. Results. The estimated C-IMT increase, for each pack-year, was more than double in women than in men (3.7\ub10.7 vs. 1.5\ub10.5 11m) with a significant gender x dose interaction (P-int=0.01). Moreover, the estimated increase in the fastest C-IMT progression associated with a unit of cigarettes/day was more than five-fold in women than in men (5.5\ub11.3 vs. 1.0\ub11.3 \ub5m/yr, P-int =0.008). Also the relationships between C-IMT and CRP (P-int =0.015), WBC (P-int =0.011) and education (P-int =0.014) were significantly different in men and women. Finally, a significant gender difference was also found in the relationship between education and smoking exposure (P-int =0.0003): Conclusions. The effects of tobacco smoking on cross-sectional subclinical atherosclerotic burden, and on atherosclerosis progression appear to be overdraw in women than in men. Inflammation and social class seems to be implicated in the complex interrelation between tobacco smoke, gender and subclinical atherosclerosis