Venous thromboembolism is the presence of a blood clot that blocks a blood vessel within the venous system; it includes deep vein thrombosis (DVT) and pulmonary embolism (PE) which can be fatal. Venous thromboembolism occurs in 44% to 90% of those patients who undergo total hip or knee replacement and who do not receive anticoagulants (blood thinning drugs).
The standard treatment is prophylaxis with an anticoagulant such as low molecular weight heparin (known as an indirect thrombin inhibitor), or warfarin or coumarin (vitamin K antagonists). New types of anticoagulants termed direct thrombin inhibitors have advantages over heparin as they can be given by mouth, do not require laboratory control and no relevant interaction with food or alcohol is known.
This review found that direct thrombin inhibitors are as effective in the prevention of major venous thromboembolism in total hip or knee replacement compared with low molecular weight heparin and vitamin K antagonists. However, the newer anticoagulants showed higher mortality and caused more bleeding than low molecular weight heparin. No severe liver complications complications were reported in the analysed studies.
The review also showed that the timing of the start of giving anticoagulants influences the results.