Duration of Prophylaxis Against Venous Thromboembolism with Enoxaparin After Surgery for Cancer - DVT Prophylaxis in oncologic surgery
The risk of venous thromboembolus (VTE) remains high for several weeks after major surgery. This study was designed to determine the optimal duration of post-operative anti-thrombotic prophylaxis with enoxaparin following abdominal surgery for cancer.
A multicenter European prospective placebo controlled trial compared 1 week and 4 weeks of 40mg of sub-q enoxaparin daily. The first dose was given 10-14 hrs preoperatively and all patients received enoxaparin for 1 week. Primary endpoints were documented post-operative pulmonary embolus by V/Q scan or pulmonary angiography, or evidence of DVT by bilateral venography performed between 25-31 days post-operative. Eligible patients were at least 40 years old, and scheduled to undergo “curative surgery” for malignant tumors of the GI tract other than the esophagus, GU tract surgery, or female reproductive organs.
609 patients received the first week of enoxaparin and 501 were randomly assigned 3 additional weeks of enoxaparin or placebo. About 80 patients from each group were excluded from analysis because venography was inconclusive or not performed. There was no difference between groups in median age of 65yrs, 60% male, 3% history of VTE, 80% had GI tract surgery, and average 3 hours duration of surgery. The overall incidence of VTE was 8.4% in the 332 patients available for analysis. The incidence was 12.0% in the group with 1wk and 4.8% with 4wks of enoxaparin (p = 0.02), a 60% reduction in risk (95%CI, 10-82%). One pulmonary embolus occurred on placebo , and the remaining DVT were found by venography. There was no increase in bleeding or difference in mortality at 5 months.
Among patients treated with surgery for abdominal or pelvic cancer, enoxaparin for 4 wks is safe and is associated with a reduced incidence of thrombosis by venography compared to 1 week of treatment. Note that enoxaparin was begun 10-14 hours pre-operatively. Placebo controlled studies previously documented the safety and efficacy of 1 week of treatment. An additional 3wks of treatment prevented 1 DVT for every 14 patients treated (NNT = 14). This study was not powered to demonstrate a reduction in clinical events, but in a meta-analysis of 6 similar trials following orthopedic surgery, the reduction in clinical events was comparable to the reduction in DVT detected by venography.
Bergovist D, Agnelli G, Cohen AT, et al for the ENOXACAN II Investigators. Duration of Prophylaxis Against Venous Thromboembolism with Enoxaparin After Surgery for Cancer. N Engl J Med 2002;346:975-80.
Keywords: Thromboembolism, Enoxaparin, Phlebography, Pulmonary Embolism, Orthopedics, Pelvic Neoplasms
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