Association of fibrinogen with quantity of coronary artery calcification measured by electron beam computed tomography

Abstract

Increased plasma fibrinogen concentration is an independent risk factor for cardiovascular disease. Fibrinogen is the main coagulation protein in plasma, a determinant of blood viscosity, and can act as a cofactor for platelet aggregation. In this study of middle-aged men and women, we examined the association between plasma fibrinogen concentration and coronary artery calcification (CAC), a marker of preclinical coronary atherosclerosis. Two hundred twenty-eight participants were selected from the community-based Epidemiology of Coronary Artery Calcification Study, in which CAC was measured noninvasively by electron beam computed tomography. One hundred fourteen participants (57 men) were selected because they had high quantities of CAC; the remaining 114 participants (57 men) were selected because they had no detectable CAC. Logistic regression models were used to investigate the association between plasma fibrinogen concentration and high quantity of CAC. In men, an increase of 1 standard deviation in fibrinogen concentration was associated with a statistically significant odds ratio of 1.6 (95% CI 1.1 to 2.5) for a high quantity of CAC. In women, the corresponding odds ratio was 2.5 (95% CI 1.6 to 4.1). Inferences from sex-specific bivariate logistic models for odds ratios adjusted individually for each coronary risk factor and C-reactive protein were similar to those from the univariate models. In women, there was also a significant interaction between fibrinogen concentration and age. According to the models, younger women with high plasma fibrinogen were more likely to have high quantities of CAC than were younger women with low plasma fibrinogen. The strength of this association was diminished in older women.