Plasma fibrinogen was measured in 4837 women aged 25-64 years as part of the Scottish Heart Health Study and Scottish MONICA population surveys. The relationships of oral contraceptive use, the menopause and hormone replacement therapy were examined. Univariate analyses found that women with a history of oral contraceptive use, premenopausal women and those on hormone replacement therapy all had significantly lower fibrinogen levels than women who had never used oral contraceptives, postmenopausal women and non-hormone replacement users respectively. These differences persisted after age standardization. On multivariate analysis, menopausal status and hormone replacement therapy had independent effects on fibrinogen levels. Together with the common risk factors, 9.9% of the total variation in plasma fibrinogen levels was explained. However, less than 1% of this was from the combined menopausal and hormonal factors. These results confirm a postmenopausal rise in fibrinogen level which may be relevant to an increased risk of coronary heart disease. In addition, a protective effect with hormone replacement therapy is noted, although this was probably due to selection bias.
PIP: Researchers analyzed 1987-1988 data on 4837 women aged 25-64 living in Scotland to determine the effects of oral contraceptive (OC) use, menopause, and hormone replacement therapy on plasma fibrinogen levels. Current smokers had higher plasma fibrinogen levels than did ex-smokers who, in turn, had higher levels than never smoker (2.51 g/1, 2.33 g/l, and 2.28 g/l, respectively). When they standardized for age, women with a history of OC use, premenopausal women, and women on hormone replacement therapy had lower plasma fibrinogen levels than did never users, postmenopausal women, and women not on hormone replacement therapy (2.34 vs. 2.39 g/l, p .001; 2.26 vs. 2.44 g/l, p .001; 2.03 vs. 2.38 g/l, p .005, respectively). The multivariate analysis indicated that menopausal status and hormone replacement therapy independently affected fibrinogen levels, but together they accounted for less than 1% of the variation of fibrinogen levels. OC use did not have an independent effect. Menopausal status and hormone replacement therapy together with the other common risk factors (e.g., smoking, age, total cholesterol, HDL/cholesterol, and body mass index) explained just 9.9% of the total variation in plasma fibrinogen level. Selection of healthier women to whom physicians administered hormone replacement therapy may explain hormone replacement therapy's protective effect. These findings verified a postmenopausal increase in fibrinogen level which may contribute to an increased risk of coronary heart disease.