LOW-MOLECULAR-WEIGHT HEPARIN (ENOXAPARIN) AS PROPHYLAXIS AGAINST VENOUS THROMBOEMBOLISM AFTER TOTAL HIP-REPLACEMENT

Background The risk of venous thromboembolism in patients undergoing t otal hip replacement is known to be high. However, the optimal duratio n of prophylaxis with anticoagulant agents after this procedure is unk nown. We sought to determine whether one month of anticoagulant therap y with the low-molecular-weight heparin enoxaparin is more effective t han enoxaparin therapy given only during the hospitalization for surge ry. Methods Two hundred sixty-two patients undergoing total hip replac ement received enoxaparin during their hospitalizations (average stay, 10 to 11 days). They were then randomly assigned to receive enoxapari n or placebo (131 patients each). Blinded outpatient therapy (or place bo) was continued long enough that the total treatment period, inpatie nt plus outpatient, was one month for each patient. Bilateral ascendin g phlebography was performed 19 to 23 days after discharge, with deep- vein thrombosis as the primary end point. Distal and proximal thrombos is, pulmonary embolism, and hemorrhage were also recorded, as were dea ths. Results Venography was adequate in 116 patients in the placebo gr oup and 117 in the enoxaparin group. We observed 43 episodes of deep-v ein thrombosis and 2 episodes of pulmonary embolism in the placebo gro up, but only 21 episodes of deep-vein thrombosis and no episodes of pu lmonary embolism in the enoxaparin group (incidence of thromboembolism , 39 percent and 18 percent, respectively; P<0.001). The difference in the incidence of proximal deep-vein thrombosis was also significant ( 24 percent and 7 percent in the placebo and enoxaparin groups, respect ively; P<0.001). Six patients in the enoxaparin group and one patient in the placebo group had hematomas at their injection sites. No patien ts died or had major complications. Conclusions There were significant ly fewer venous thromboembolic complications in patients undergoing el ective hip replacement when prophylaxis with enoxaparin was given for a total of one month, rather than only during the hospitalization. (C) 1996, Massachusetts Medical Society.