Efficacy of prophylactic warfarin for prevention of thalidomide-related deep venous thrombosis

Background: Deep venous thrombosis (DVT) is a common complication of thalidomide treatment. There is little information to guide clinicians in selecting effective preventive treatments and physician practice varies. We sought to determine whether prophylactic anticoagulation with warfarin prevents DVT related to thalidomide treatment. Methods: We reviewed the records of 131 patients receiving thalidomide for a variety of indications. Fifty-five patients were prescribed warfarin with the intent of preventing DVT. Thirty-seven patients received warfarin at a dose of 1-2 mg per day (low dose) and. 18 received a dose intended to raise the INR to 2-3 (high dose). Results: Twenty-one of the 131 patients developed venous thrombosis during thalidomide treatment. Eighteen of the 76 patients (23.7%) who were not prescribed prophylactic anticoagulation developed DVT compared to 3 of the 55 patients (5.5%) who were prescribed any dose of prophylactic warfarin (P = 0.010). Only 1 of the 37 patients who received low-dose warfarin developed DVT (P = 0.011). Bleeding complications occurred in 4 patients, all of whom were receiving high-dose warfarin. Conclusion: Prophylactic anticoagulation with warfarin reduces the risk of thrombosis during thalidomide treatment. Low-dose warfarin may be as effective as higher dose treatment and may result in fewer bleeding complications.