Efficacy of Prophylactic Anticoagulation To Prevent Thalidomide-Related Deep Venous Thrombosis.

Deep venous thrombosis (DVT) is a known complication of treatment with thalidomide, occurring in up to 25% of patients. Although prophylactic anticoagulation has been recommended by some authors, there are few data available to assess whether this is beneficial. We reviewed the records of 131 patients receiving thalidomide for a variety of indications. Ninety-three patients had multiple myeloma, 12 had MDS or myelofibrosis and 26 had solid tumors. The mean and median dose of thalidomide was 200 mg/day. 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). Of 25 patients on single-agent thalidomide; only 4 received warfarin. Twenty-one of the 131 patients developed venous thrombosis during thalidomide treatment. All patients who developed DVT were receiving thalidomide in combination with dexamethasone or some form of chemotherapy. Only one patient who developed DVT was receiving thalidomide at more than 200 mg/day. Eighteen of the 76 patients (23.7%) who were not prescribed prophylactic anticoagulation developed DVT compared to three of the 55 patients (5.5%) who were prescribed any dose of prophylactic warfarin (p=.010). Only one of the 37 patients who received low dose warfarin developed DVT (p=.011). Bleeding complications occurred in 4 patients who were all receiving high dose warfarin. Two previous unrandomized studies suggested that low dose warfarin was not protective of DVT but both used high doses of thalidomide (250–400 mg) in combination with other agents which is no longer recommended. Our study suggests that low dose warfarin prophylaxis may be sufficient and safe for patients receiving thalidomide at a dose of 200 mg/day in combination with other agents.