EFFICACY AND SAFETY OF A LOW-MOLECULAR-WEIGHT HEPARIN AND STANDARD UNFRACTIONATED HEPARIN FOR PROPHYLAXIS OF POSTOPERATIVE VENOUS THROMBOEMBOLISM - EUROPEAN MULTICENTER TRIAL

A randomized, double-blind multicenter trial was performed to compare the safety and efficacy of a new low-molecular-weight heparin (LMWH) ( LU 47311, Clivarine) and standard unfractionated heparin for the proph ylaxis of postoperative venous thromboembolism. Altogether 1351 patien ts scheduled to undergo abdominal surgery were included. Main outcome measures included the incidence of thromboembolic events (deep vein th rombosis, pulmonary embolism, or both) and bleeding complications, inc luding wound hematoma. A total of 655 patients received 1750 anti-Xa I U of LMWH plus a placebo injection daily; 677 patients received 5000 I U of unfractionated heparin (UFH) twice a day. Both drugs were found t o be equally effective, as 4.7% of patients in the LMWH group and 4.3% in the UFH group developed postoperative thromboembolic complications . However, the incidence of bleeding complications was significantly r educed in the LMWH group: 55 (8.3%) patients in the LMWH group and 80 (11.8%) in the UFH group developed bleeding complications, a relative risk (RR) of 0.70 (95% CI 0.51-0.97; p = 0.03); wound hematoma occurre d in 29 (4.4%) of the LMWH group compared with 55 (7.7%) in those in t he UFH group for an RR of 0.57 (95% CI 0.37-0.88; p = 0.01). This stud y confirmed that a very low dose of 1750 anti-Xa IU daily of this new LMWH is as effective as 10,000 IU of UFH for preventing postoperative deep vein thrombosis. At this dose its administration is associated wi th a significant reduction in the risk of bleeding including wound hem atoma.