A Randomized Controlled Trial of a Low-Molecular-Weight Heparin (Enoxaparin) to Prevent Deep-Vein Thrombosis in Patients Undergoing Elective Hip Surgery

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Abstract
There is experimental evidence that low-molecular-weight fractions of heparin are as effective as the standard form but cause less bleeding. We therefore performed a double-blind, randomized trial comparing PK10169 low-molecular-weight heparin with placebo for the prevention of venous thrombosis in patients undergoing elective hip surgery. Prophylactic treatment with a fixed dose was begun postoperatively and continued for 14 days. Fifty patients in each treatment group underwent surveillance with [125l]fibrinogen leg scanning and impedance plethysmography. In the first 24 patients, venography was performed only if either surveillance test was positive. Because the rate of venous thrombosis detected in those patients was unexpectedly low, 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 percent) given PK10169 heparin and 20 patients (51.3 percent) given placebo (P = 0.0002); the corresponding rates for proximal-vein thrombosis were 5.4 percent and 23.1 percent, respectively (P = 0.029). In the entire group of 100 patients, venous thrombosis occurred in 12 percent of those given PK10169 heparin and 42 percent of those given placebo (P = 0.0007), and the corresponding rates for proximal-vein thrombi were 4 percent and 20 percent, respectively (P = 0.014). The observed hemorrhagic rate was 4 percent in each treatment group.