Prevention of postoperative venous thrombosis: a randomized trial comparing unfractionated heparin with low molecular weight heparin in patients undergoing total hip replacement.

A double blind randomized trial comparing subcutaneous enoxaparin (40 mg once daily) with standard unfractionated calcium heparin administered at a dose of 5,000 units every 8 hours in patients undergoing elective hip replacement has been performed. Treatment regimens began 12 hours preoperatively with enoxaparin, 2 hours preoperatively with standard unfractionated calcium heparin, and were continued for 15 days or until discharge. Venography was performed in all patients. Two hundred thirty-seven patients were included in the study: 113 received unfractionated heparin and 124 received enoxaparin. The incidence of proximal deep vein thrombosis was reduced from 18.5% in the unfractionated heparin group to 7.5% in the enoxaparin group (p = 0.014), and the incidence of total deep vein thrombosis was similarly reduced from 25% to 12.5% (p = 0.03). There were two major bleeding episodes and one minor bleed in the enoxaparin group compared to two minor bleeds in the unfractionated heparin group. Patients who received enoxaparin required fewer red blood cell transfusions and had a significantly higher hemoglobin on postoperative days 3 and 4. Thus prophylaxis with enoxaparin, 40 mg once daily, is simple, safe and more effective than standard low dose unfractionated heparin in preventing deep vein thrombosis in patients undergoing elective hip replacement.

[Double-blind randomized comparative study of enoxaparin and standard heparin in the prevention of thromboembolic disease during insertion of total hip replacement]. / Etude comparative en double aveugle randomisée de l'enoxaparine et de l'héparine standard dans la prévention de la maladie thrombo-embolique lors de la mise en place d'une prothèse totale de hanche.

237 patients with a non-traumatic disease of the hip requiring total hip replacement entered a multicentre trial. Treatments were allocated at random in a double-blind manner: 113 patients received 5000 IU of standard heparin t.d.s.; 124 patients received enoxaparin 40 mg once a day. Treatment lasted from 10 to 15 days until bilateral ascending phlebography of the lower limbs (BAPLL) was performed. Its effectiveness was assessed by the results of BAPLL, by evaluation of the risk of bleeding on examination of the surgical wound, by the units of blood required for perfusion and by daily blood count and differential. BAPLL was performed in 228 patients: 15 phlebographies (12.5 p. 100) were positive in the 120 assessed patients of the enoxaparin group, while 27 (25 p. 100) were positive in the 108 assessed patients of the standard heparin group (p = 0.014). Proximal deep vein thrombosis was significantly (p = 0.03) less frequent in the enoxaparin group (7.5 p. 100) than in the standard heparin group (18.5 p. 100). Pulmonary embolism was observed in a patient on standard heparin. The units of blood required for perfusion were significantly (p = 0.03) smaller in the enoxaparin group (3.37 +/- 1.81 U) than in the standard heparin group (3.84 +/- 1.70 U). Thus, one single subcutaneous injection of enoxaparin 40 mg daily was significantly more effective and safer than standard heparin 5000 IU t.d.s. in the prevention of deep vein thrombosis after total hip replacement.