Association between fibrinogen and carotid intima-media thickness by smoking status

Abstract

Fibrinogen may be associated with carotid intima-media thickness (CIMT). But some studies did not show the significant association between fibrinogen and CIMT. Smoking is one of the risk factors for atherosclerosis and also related with increasing the level of fibrinogen. Thus, our hypothesis is that the association between fibrinogen and CIMT can be modified by smoking status.Fibrinogen was measured in 277 men who were aged 40-87 years, without history of myocardial infarction and cerebrovascular diseases. Maximum and three point mean values (defined as IMTmax and IMTtpm, respectively) of CIMT measured by ultrasonography were used as continuous variables. Plaque was defined when IMTmax > 1.0 mm or an area of focal wall thickening was 100% greater than the neighboring sites. Independent association between fibrinogen and CIMT by smoking status was assessed by linear regression analysis and logistic regression analysis.Fibrinogen was positively associated with CIMT even after adjustment for potential confounders such as age, body mass index, systolic blood pressure, fasting glucose, and ratio of total cholesterol to high-density lipoprotein cholesterol in current smokers (Standardized ß for IMTmax = 0.25, p = 0.021; Standardized ß for IMTtpm = 0.21, p = 0.038). But there is no significant association between fibrinogen and CIMT in former (Standardized ß for IMTmax = -0.07, p = 0.421; Standardized ß for IMTtpm = -0.04, p = 0.605) and never smokers (Standardized ß for IMTmax = -0.01, p = 0.955; Standardized ß for IMTtpm = -0.04, p = 0.692). Odds ratio for having plaque that increased per 1 standard deviation of fibrinogen was 2.04 (95% CI, 1.08 - 3.85) in current smokers when adjusted for potential confounders, but not significant in former smokers (OR = 0.68, 95% CI = 0.42-1.09), or never smokers (OR = 0.98, 95% CI = 0.55-1.77). Our findings suggest that cigarette smoking may role as an effect modifier to the association between fibrinogen and CIMT.