LOW-MOLECULAR-WEIGHT HEPARIN IN THE TREATMENT OF PATIENTS WITH VENOUSTHROMBOEMBOLISM

Background Low-molecular-weight heparin is known to be safe and effect ive for the initial Treatment of patients with proximal deep-vein thro mbosis. However, its application to patients with pulmonary embolism o r previous episodes of thromboembolism has not been studied. Methods W e randomly assigned 1021 patients with symptomatic venous thromboembol ism to fixed-dose, subcutaneous low-molecular-weight heparin (revipari n sodium) or adjusted-dose, intravenous unfractionated heparin. Oral a nticoagulant therapy with a coumarin derivative was started concomitan tly and continued for 12 weeks, Approximately one third of the patient s had associated pulmonary embolism, The outcome events studied over t he 12 weeks were symptomatic recurrent venous thromboembolism, major b leeding, and death. We sought to determine whether low-molecular-weigh t heparin is at least equivalent to unfractionated heparin in patients with venous thromboembolism. Results Twenty-seven of the 510 patients assigned to low-molecular-weight heparin (5.3 percent) had recurrent thromboembolic events, as compared with 25 of the 511 patients assigne d to unfractionated heparin (4.9 percent). The difference of 0.4 perce ntage point indicates that the two therapies have equivalent value acc ording to our predetermined definition of equivalence. Sixteen patient s assigned to low-molecular-weight heparin (3.1 percent) and 12 patien ts assigned to unfractionated heparin (2.3 percent) had episodes of ma jor bleeding (P=0.63), and the mortality rates in the two groups were 7.1 percent and 7.6 percent, respectively (P=0.89). Conclusions Fixed- dose, subcutaneous low-molecular-weight heparin is as effective and sa fe as adjusted-dose, intravenous unfractionated heparin for the initia l management of venous thromboembolism, regardless of whether the pati ent has pulmonary embolism or a history of venous thromboembolism. (C) 1997, Massachusetts Medical Society.