Summary

Moderate alcohol consumption is associated with lower levels of several coagulation factors. It is an established protective factor for cardiovascular disease; however, the effect on venous thrombosis is unknown. In a large population-based case-control study, we evaluated the association between alcohol consumption and the risk of venous thrombosis.The MEGA study included consecutive patients with a first venous thrombosis between March 1999 and September 2004 from six anticoagulation clinics in the Netherlands.Partners of patients were asked to participate, and additional controls were recruited using a random digit dialling method.All participants completed a standardized questionnaire, and blood samples were collected. A total of 4,423 patients and 5,235 controls were included in the analyses. Alcohol consumption was associated with a reduced risk of venous thrombosis, with 2–4 glasses per day resulting in the largest beneficial effect (odds ratio [OR] 0.67, 95% confidence interval [CI95] 0.58–0.77) compared to abstainers.The effect was more pronounced in women (OR 0.66, CI95 0.53–0.84) than men (OR 0.82, CI95 0.63–1.07) and also more striking for pulmonary embolism (OR 0.56, CI95 0.46–0.70) than for deep venous thrombosis of the leg (OR 0.74, CI95 0.63–0.88). Compared to abstainers, fibrinogen levels were decreased in individuals who consumed alcohol (maximum decrease: 0.30 g/l). FactorVII and vonWillebrand levels were mildly decreased in these individuals but not consistently over the categories of alcohol consumption. In conclusion, alcohol consumption is associated with a reduced risk of venous thrombosis, which may be in part mediated by decreased fibrinogen levels.