Elevated plasma fibrinogen and increased fibrin turnover among healthy women who both smoke and use low-dose oral contraceptives - A preliminary report

Among users of low-dose oral contraceptives (OC), cardiovascular diseases o ccur mainly in smokers. The mechanisms by which OC and smoking increase the risk for arterial thrombotic risk have not been adequately explained. Epid emiological evidence suggests that changes in blood coagulation and fibrino lysis may play an important role as determinants of thrombotic events. Ther efore, we have investigated the associations of OC and smoking with haemost atic variables among 194 premenopausal healthy women. Fourty women were cur rent users of low-dose OC and 62 women were smokers. After adjustment for a ge and body mass index, mean values of factor XIIa, factor VII activity and antigen. fibrinogen, D-dimer, global fibrinolytic capacity were significan tly higher in OC users than in non-users, Mean levels of PAI activity and t -PA antigen were significantly lower in OC users than in non-users. Smokers had significantly higher mean values of fibrinogen than non-smokers. Two-w ay analysis of variance showed that the differences in mean levels of fibri nogen and D-dimer between OC users and non users were restricted to smokers . The positive and significant interactions between OC use and smoking in t heir effects on haemostatic variables were consistent with respect to age a nd type Of OC. These preliminary data suggest that elevated plasma levels o f fibrinogen and intravascular fibrin deposition may play a role in the pat hogenesis of arterial thrombotic disease among women who are both low-dose OC users and smokers.