RISK OF DEEP-VENOUS THROMBOSIS AFTER HOSPITAL DISCHARGE IN PATIENTS HAVING UNDERGONE TOTAL HIP-REPLACEMENT - DOUBLE-BLIND RANDOMIZED COMPARISON OF ENOXAPARIN VERSUS PLACEBO

Background The risk of deep-vein thrombosis (DVT) and pulmonary emboli sm after total hip replacement (THR) surgery may persist after hospita l discharge, but the extent of the risk is not known. We carried out a single-centre, prospective, randomised, double-blind trial with the a ims of quantifying this risk and assessing the efficacy of continued p rophylactic treatment. Methods At hospital discharge 13-15 days after surgery, we recruited 179 consecutive THR patients who had no DVT visi ble on bilateral ascending venography of the legs. The patients were r andomly assigned subcutaneous enoxaparin (40 mg, once daily; n=90) or placebo (n=89) for 21 (19-23) days. The primary endpoint was the occur rence of DVT or pulmonary embolism. Venography was repealed at the end of 21 days' treatment or earlier if necessary. Findings There were no deaths and no symptomatic pulmonary embolisms during the study or fol low-up periods. Of 173 patients with evaluable venograms, intention-to -treat analysis of efficacy showed that the rate of DVT at day 21 afte r discharge was significantly lower in the enoxaparin group than in th e placebo group (6 [7.1%] vs 17 [19.3%], p=0.018). Distal DVT was dete cted in one (1.2%) patient in the enoxaparin group and in ten (11.4%) patients in the placebo group (p=0.006). Proximal PVT was observed in five (5.9%) patients in the enoxaparin group and in seven (7.9%) patie nts in the placebo group (p=0.592). A perprotocol analysis of efficacy in 155 patients confirmed these findings. Safety was good; three mino r bleeding episodes occurred in the enoxaparin group and one in the pl acebo group, but none of these episodes necessitated withdrawal from t he study. Interpretation In patients who have undergone THR surgery, a re without venogram-proven DVT at hospital discharge, and do not recei ve antithrombotic prophylaxis after discharge, the risk of tale-occurr ing DVT remains high at least until day 35 after surgery. Continued pr ophylaxis with enoxaparin is effective and safe in reducing this risk.