Plasma fibrinogen concentrations and risk of stroke and its subtypes among Japanese men and women

Background and Purpose-We aimed to examine the impact of fibrinogen concentrations on the incidence of stroke. Methods-We examined the association between fibrinogen and risk of total stroke and stroke subtypes in an 11-year prospective study of 4608 men and 7589 women aged 40 to 79 years with no history of stroke and/or coronary heart disease. The analysis was repeated, stratified by smoking status, to examine whether the association between fibrinogen and stroke was modified by smoking. Results-There were 317 incident total strokes comprising 103 hemorrhagic strokes (70 intraparenchymal hemorrhages [22.1% of strokes], 33 subarachnoid hemorrhages [10.4%]), 206 ischemic strokes (65.0%), and 8 strokes of undetermined type (2.5%). The multivariable hazard ratio (95% CI) for the highest versus lowest fibrinogen quartiles after adjustment for age, sex, area, and known cardiovascular risk factors was 2.5 (1.3 to 5.0), P < 0.01, for hemorrhagic stroke and 3.2 (1.4 to 7.4), P < 0.01, for intraparenchymal hemorrhage. There was no positive association of fibrinogen with risk of ischemic stroke or subarachnoid hemorrhage. Among never-smokers, the multivariable hazard ratio (95% Cl) for the highest versus lowest fibrinogen quartiles was 3.5 (1.3 to 9.3), P=0.01, for hemorrhagic stroke and 4.4 (1.3 to 15.2), P=0.02, for intraparenchymal hemorrhage. Conclusions-High plasma fibrinogen concentration can be a predictor for risk of intraparenchymal hemorrhage.