Extended anticoagulation therapy for the primary and secondary prevention of venous thromboembolism.

Extending the period of anticoagulation is an active area of investigation in both primary and secondary prevention of venous thromboembolic disease. In orthopaedic surgery, particularly in patients undergoing hip surgery, there is a growing interest in using extended anticoagulation beyond that traditionally given in the postoperative period using low-molecular weight heparin, oral anticoagulants, or newer agents such as fondaparinux sodium. Most studies show a benefit to extending anticoagulation without a considerable increase in major bleeding. There have been several large clinical trials addressing the question of extending oral anticoagulation in secondary prevention of venous thromboembolism (VTE). Just how long anticoagulation should be given in the treatment of venous thromboembolic disease remains an open question, depending on the nature of the initial VTE, associated patient risk factors and the risks of major bleeding. Future directions include the use of newer agents for anticoagulation as well as methods of better defining who will benefit most from extended anticoagulation based on an identification of risk factors with the aid of markers such as D-dimer or residual vein thrombosis.