A systematic overview including more than 8000 patients from randomized trials on antiplatelet primary thromboprophylaxis suggested that antiplatelet therapy was effective to prevent deep vein thrombosis and pulmonary embolism in high risk patients (Antiplatelet Trialists' Collaboration).13 Antiplatelet therapy was associated with a relative risk reduction [RRR] of 39%; (p=0.00001) in the incidence of venous thromboembolism in high-risk medical patients or undergoing orthopedic or general surgery. There was no excess in cerebral or fatal bleeding.