Summary

Although obesity is associated with increased cardiovascularrisk, the mechanism has not been fully explained. Since thrombosisis a critical component of cardiovascular disease, weexamined the relationship between obesity and hemostatic factors.We studied 3230 subjects (55% females, mean age 54years) without a history of cardiovascular disease in cycle 5 ofthe Framingham Offspring Study. Obesity was assessed by bodymass index and waist-to-hip ratio. Fasting blood samples wereobtained for fibrinogen, plasminogen activator inhibitor (PAI-1)antigen, tissue plasminogen activator (tPA) antigen, factor VIIantigen, von Willebrand factor (VWF), and plasma viscosity.Body mass index was directly associated with fibrinogen, factor VII, PAI-1 and tPA antigen in both men and women (p<0.001)and with VWF and viscosity in women. Similar associationswere present between waist-to-hip ratio and the hemostaticfactors.With minor exceptions for VWF and viscosity, all associationspersisted after controlling for age, smoking, total andHDL cholesterol, triglycerides, glucose level, blood pressure,and use of antihypertensive medication. The associationbetween increased body mass index and waist-to-hip ratio andprothrombotic factors and impaired fibrinolysis suggests thatobesity is a risk factor whose effect is mediated in part by aprothrombotic state.