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 warfarin 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, prophylactic dose had comparable benefit-to-risk ratios in the prevention of thrombosis associated with central venous catheters in cancer patients.