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.