Associations of smoking status with carotid atherosclerosis: Mediated role of blood indexes and blood pressure

Background and aims: We aimed to assess the relationship between smoking status and carotid atherosclerosis (CA) with different manifestations and to explore the underlying mechanisms.

Methods and results: A total of 60,655 middle-aged and elderly participants were recruited. Logistic regression models were used to examine the association of smoking, various blood indexes [i.e., blood pressure, blood lipid, glycated hemoglobin (HbA1c) and homocysteine (Hcy)] with CA in different manifestations including carotid intima-media thickness (cIMT), plaques, and stenosis. Compared with nonsmokers, current smokers were associated with a higher prevalence of CA (OR = 3.48, 95%CI: 3.21-3.77) and its specific manifestations including cIMT (OR = 2.66, 95%CI: 2.42-2.93), plaques (OR = 3.67, 95%CI: 3.35-4.02) and stenosis (OR = 2.04, 95%CI: 1.64-2.54), after adjusting for potential confounders. Former smokers were also associated with an increased prevalence of CA (OR = 1.82, 95%CI: 1.54-2.14), cIMT (OR = 1.39, 95%CI: 1.14-1.69), plaques (OR = 2.04, 95%CI: 1.71-2.44) and stenosis (OR = 1.72, 95%CI: 1.18-2.51), but the associations were consistently weaker than that of the current smokers. The prevalence of CA, cIMT, plaques and stenosis among current smokers was positively associated with pack-years of cigarette smoking, partially mediated by SBP, HbA1c, TG, HDL-C and Hcy with a mediated proportion of 1.12%, 3.28%, 6.33%, 6.01% and 12.7%, respectively. Stratified analysis by sex showed a significantly higher CA among the current male smokers than females.

Conclusions: Current and former smoking was associated with increased carotid atherosclerosis, predominantly by current male smokers. A positive gradient between pack-years and carotid atherosclerosis among current smokers is partially mediated by SBP, HbA1c, TG, HDL-C and Hcy.