Efficacy of a postoperative regimen of enoxaparin in deep vein thrombosis prophylaxis

Venous thromboembolism is a common complication in patients undergoing elective hip replacement, in whom the incidence of calf vein thrombosis is 40% to 60%; proximal vein thrombosis, 20%; and fatal pulmonary embolism, 1% to 2% when prophylaxis is not used. A double-blind, randomized trial comparing low-molecular-weight heparin (enoxaparin) with placebo for the prevention of venous thrombosis in patients undergoing elective hip surgery was carried out. Prophylactic treatment with a fixed dose was begun postoperatively and continued for 14 days. Fifty patients in each treatment group underwent surveillance with 125I-fibrinogen leg scanning and impedance plethysmography. In the first 24 patients, venography was performed only if their surveillance test was positive. Venography was requested in the remaining 76 patients even if the screening tests were negative; in this latter group, venous thrombosis occurred in 4 patients (10.8%) given enoxaparin and 20 patients (51.3%) given placebo (p = 0.0002). The corresponding rates for proximal vein thrombosis were 5.4% and 23.1%, respectively (p = 0.029). In the entire group of 100 patients, venous thrombosis occurred in 12% of those given enoxaparin and 42% of those given placebo (p = 0.0007). The corresponding rates for proximal vein thrombi were 4% and 20%, respectively (p = 0.014). The observed hemorrhagic rate was 5% in each treatment group. The results of this study show that prophylaxis with fixed-dose enoxaparin is effective and safe for patients undergoing elective hip replacement.