PROPHYLAXIS OF VENOGRAPHICALLY DIAGNOSED DEEP-VEIN THROMBOSIS IN GASTROINTESTINAL SURGERY

Objective: To compare enoxaparin and dextran 70 for the prophylaxis of venographically diagnosed deep vein thrombosis (DVT) after gastrointe stinal operations. Design: Part 1: randomised double blind trial; Part 2: single blind study with historical controls. Setting: Eight Norweg ian hospitals. Subjects: 381 Patients undergoing elective gastrointest inal operations. Interventions: Part 1 (n = 329): enoxaparin 20 mg sub cutaneously starting two hours before operation and continuing until t he patient was fully mobilised or had had 10 injections and a placebo infusion of 0.9% sodium chloride, or dextran 70500 mi at the start of the operation, on the evening of operation, and on the first, third, a nd fifth postoperative days and placebo subcutaneous injections. Part 2 (n = 52): enoxaparin 40 mg in the same regimen as part 1 (compared w ith 39 historical controls). Venograms 4-6 days postoperatively. Main outcome measure: Venographically confirmed DVT. Results: Part 1: Becau se of the high overall incidence of DVT an interim analysis was done w hich showed 33/101 DVT (33%) among high risk patients in the enoxapari n 20 mg group and 33/107 (31%) in the dextran 70 group. The correspond ing figures for patients at medium risk were 2/27 (7%) for enoxaparin 20 mg and 5/27 (19%) for dextran 70 (95% confidence interval (CI) for the difference-11.9 to 9.8). Part 2: the dose of enoxaparin was theref ore increased to 40 mg and prophylaxis restricted to patients with can cer. There were 6/49 DVT (12%), which was compared with a random sampl e from the dextran 70 group from part 1 (historical controls) in which the incidence was 15/39 (38%, 95% CI of the difference 4.0 to 8.4). T here were no pulmonary emboli, only 4 thrombi were above the knee and there were 4, 1 and 3 clinical DVT in the 20 mg and 40 mg enoxaparin, and dextran 70 groups, respectively. Conclusions: Enoxaparin 20 mg and dextran 70 are effective prophylaxis for patients at medium risk, but enoxaparin 40 mg is required for those at high risk.