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Excerpt
Abstracts from Literature
Synopsis: Even though the optimal duration of postoperative thromboprophylaxis is unknown, this article from the INTOXICANT II study proves that 4 weeks of prophylaxis against venous thromboembolism with enoxaparin is a safe regimen enoxaparin prophylaxis for 1 week.
Source: Bergqvist D, Agnelli G, Cohen AT, et al. Duration of prophylaxis against venous thromboembolism with enoxaparin after surgery for cancer. N Engl J Med. 2002;346:975–980.
The optimum duration of anticoagulation in various medical and surgical circumstances has been a topic of much debate and research in the last decade or so. The justification for the use of thromboprophylaxis is supported by the high prevalence of deep vein thrombosis (DVT) among sick hospitalized patients. Postoperative DVT is present in 6% to 7% of general surgery patients; most DVT does not have clinical manifestations and therefore may not be detected. It is therefore not appropriate to wait for the fatal pulmonary embolism (PE), which may be the first expression of a silent VTE. The widespread application of effective methods of prophylaxis is safer and more cost effective than selective and intense surveillance that includes serial venous dopplers. The study under discussion was done after the ENOXACAN I study, which showed that the average incidence of DVT was 15%, occurring in patients receiving enoxaparin for 10 days after abdominal surgery for cancer. The risk for untreated patients has been shown in earlier studies to be as high as 29%. Clinical risk factors include the following: increasing age, prolonged immobility, stroke, or paralysis, previous VTE, cancer and its treatment, major surgery involving the abdomen, pelvis, and lower extremities, trauma, obesity, varicose veins, cardiac dysfunction, indwelling central venous catheters, inflammatory bowel disease, nephrotic syndrome, and pregnancy or estrogen use [Geerts WH, et al. Prevention of venous thromboembolism. Chest. 2001;119:132S–175S].
This study was conducted in 37 centers in Western Europe and Israel during the 21 months between October 1998 and June 2000. All cancer patients 40 years of age or older with a life expectancy of at least 6 months were considered eligible. They were scheduled to undergo elective and open curative surgery for a malignancy of the gastrointestinal tract (excluding esophagus), genitourinary tract, or female reproductive organs. The planned duration of each surgery was >45 minutes, and all patient were to receive general anesthesia. The study excluded patients with hepatic or renal failure, known hypersensitivity to either low-molecular-weight heparin (LMWH) or radiographic contrast media, cerebral thrombosis or hemorrhage, neurosurgery in the past 6 months, known cerebral metastatic disease, generalized bleeding disorders, endocarditis, active peptic ulcer, VTE within the previous 3 months, uncontrolled arterial hypertension, treatment with heparin compounds or oral anticoagulant agents within 5 days before surgery, and pregnancy or lactation. Informed consent was obtained from each patient, and an ethics committee in each country approved the study.
The study under discussion was a double-blind, placebo-controlled, randomized multicenter trial. Both groups received enoxaparin 40 mg once daily for 6 to 10 days after surgery, with the first dose given 10 to 14 hours preoperatively. After this, each patient was randomized to one of the two groups. One group was assigned to placebo, whereas the other received enoxaparin for another 19 to 21 days to complete a total treatment period of 25 to 31 days. Even though graduated compression stockings were allowed, intermittent pneumatic compression and electrical calf muscle stimulation were not. Competent patients, caregivers, or district nurses were allowed to administer injections. The compliance was checked by counts of the remaining doses and by the review of the documentation.
