Long term outpatient prophylaxis for venous thromboembolism

Recent reductions in the incidence of postoperative venous thromboembolism are related to the widespread use of prophylactic anticoagulants, but many uncertainties about the most effective ways to use thromboprophylaxis remain. Orthopedic patients are at high risk of thromboembolism, and the trend towards shorter hospital stays means that they may receive less than the recommended 7 to 10 days of prophylaxis. Longer periods of thromboprophylaxis may be beneficial for high risk patients. The relative rarity of symptomatic deep-vein thrombosis and pulmonary embolism means that very large patient populations are required for studies that rely on clinical endpoints, but studies using venographic endpoints have shown 30 days of prophylaxis with low molecular weight heparin (LMWH) to be more effective than 7 days. Other factors that may influence the efficacy of thromboprophylaxis include the timing of the first injection and the choice of agent.