Hemostatic variables in Japanese and Caucasian men. Plasma fibrinogen, factor VIIc, factor VIIIc, and von Willebrand factor and their relations to cardiovascular disease risk factors.

Mortality rates of coronary heart disease are much lower and hemorrhagic stroke rates are higher in Japanese than in Caucasians. To investigate whether population differences in plasma concentrations of coagulation factors are consistent with these mortality differences, the authors examined, in 1987, a total of 136 men aged 34-55 years in four different samples: rural Japanese living in Akita, Japan; urban Japanese living in Osaka, Japan; and Japanese Americans and Caucasian Americans living in Minneapolis-St. Paul, Minnesota. The mean plasma fibrinogen level in Caucasians was 290 mg/dl, which was significantly higher than that in each of the Japanese samples (223-250 mg/dl; test for difference: p less than 0.001). The mean coagulation activities of factor VII and factor VIII (factor VIIc and factor VIIIc) were higher in Caucasian and Japanese Americans than in rural and urban Japanese (p less than 0.01 for factor VIIc and p = 0.03 for factor VIIIc). von Willebrand factor did not differ significantly across the populations. The relations of these coagulation factors with other cardiovascular risk factors (age, body mass index (weight (kg)/height (m)2), blood pressure, serum total cholesterol, serum triglyceride, cigarette smoking, and alcohol intake) were also examined. Mean plasma fibrinogen was consistently higher in current smokers than in nonsmokers within each sample. Factor VIIc and factor VIIIc levels were positively associated with serum total cholesterol and serum triglyceride. No consistent associations were seen between von Willebrand factor and cardiovascular risk factors. After the authors controlled for these covariates, mean fibrinogen and factor VIIc levels remained significantly different, but factor VIIIc levels did not. Different levels of coagulation factors across these samples are probably attributable to differences in environmental factors, especially diet, as well as genetic differences between Caucasians and Japanese. Furthermore, the differences in plasma fibrinogen and factor VIIc levels may explain part of the difference in mortality from cardiovascular disease across these populations.