Outpatient management of anticoagulation therapy

The Seventh American College of Chest Physicians (ACCP) Conference on Antithrombotic and Thrombolytic Therapy provides guidelines for outpatient management of anticoagulation therapy. The ACCP guidelines recommend short-term warfarin therapy, with the goal of maintaining an International Normalized Ratio (INR) of 2.5 +/- 0.5, after major orthopedic surgery. Therapy for venous thromboembolism includes an INR of 2.5 +/- 0.5, with the length of therapy determined by associated conditions. For patients with atrial fibrillation, the INR is maintained at 2.5 +/- 0.5 indefinitely; for most patients with mechanical valves, the recommended INR is 3.0 +/- 0.5 indefinitely. Use of outpatient low-molecular-weight heparin (LMWH) is as safe and effective as inpatient unfractionated heparin for treatment of venous thromboembolism. The ACCP recommends starting warfarin with unfractionated heparin or LMWH for at least five days and continuing until a therapeutic INR is achieved. Because patients with venous thromboembolism and cancer who have been treated with LMWH have a survival advantage that extends beyond their venous thromboembolism treatment, the ACCP recommends beginning their therapy with three to six months of LMWH. When invasive procedures require the interruption of oral anticoagulation therapy, recommendations for bridge therapy are determined by balancing the risk of bleeding against the risk of thromboembolism. Patients at higher risk of thromboembolization should stop warfarin therapy four to five days before surgery and start LMWH or unfractionated heparin two to three days before surgery.