In the Jichi Medical School Cohort Study, a multi-center study aiming at the elucidation of factors underlying cerebral vascular diseases and myocardial infarction, we have attempted to see whether plasma fibrinogen, known among Caucasians as a risk factor for stroke and myocardial infarction, contributed also to the incidence of such diseases among Japanese. The blood samples were obtained from 3815 inhabitants, 1563 men and 2252 women, ranging from 40 to 79 years of age, in nine districts selected from Kanto to Kyushu during the periods of July-November, 1992 and May-November, 1993. The plasma fibrinogen level was found to be higher in women (the mean±SD: 244.9±52.1mg/dl) than in men (242.7±56.3mg/dl), although these values were apparently reduced as compared with those reported in previous studies on Caucasians. Furthermore, there was a significant increase in plasma fibrinogen after the menopause in women as reported elsewhere, suggesting possible participation of sexual hormones in the regulation of fibrinogen level in plasma. The plasma fibrinogen was significantly increased in current smokers, alcohol non-drinkers and subjects with a history of cerebral vascular disease.
The cross-sectional data showed that plasma fiblinogen levels were associated with some cardiovascular risk factors. Prospective studies are needed to elucidate the causality between the higher plasma fibrinogen level and the cardiovascular diseases in Japan.