Low-molecular-weight heparin (nadroparin) and very low doses of warfarin in the prevention of upper extremity thrombosis in cancer patients with indwelling long-term central venous catheters:: a pilot randomized trial

Background and Objectives. Upper extremity thrombosis is a major complication of central venous catheters implanted for chemotherapy in cancer patients. Vitamin K antagonists and low-molecular-weight heparins have been recommended in this-setting, but their relative benefit-to-risk ratios have never been compared. Design and Methods. A prospective, randomized, open, parallel-group, multicenter trial was performed comparing the antithrombotic efficacy and safety of war-farin and the low-molecular-weight heparin, nadroparin, in cancer patients who had undergone central venous catheter implantation. Warfarin was given orally at a fixed daily dose of 1 mg and nadroparin was, injected subcutaneously at a fixed daily dose of 2,850 IU for 90,days, or until venographically-confirmed, thrombosis occurred. The primary efficacy outcome was the occurrence of upper extremity thrombosis confirmed-by venography performed 90 days after insertion of the catheter, or earlier if symptoms of thrombosis had appeared. Safety end-points were bleeding and thrombocytopenia. Results. Fifty-nine patients were included in the study. A total of 21 and 24 patients in the nadroparin and warfarin groups, respectively, were evaluable for primary efficacy. Six out of the 21 patients in the nadroparin group (28.6%) and 4 out of the 24 patients in the warfarin group (16.7%) had venographically-documented upper extremity thrombosis at day 90 (p=0.48). Safety was satisfactory and similar with both treatments. Interpretation and Conclusions. Warfarin. at a fixed, very low dose and nadroparin at a fixed, prophyladic dose had comparable benefit-to-risk ratios in the prevention of thrombosis, associated with central venous catheters in cancer patients.