Prolonged prophylaxis with dalteparin to prevent late thromboembolic complications in patients undergoing major abdominal surgery: a multicenter randomized open-label study

J Thromb Haemost. 2006 Nov;4(11):2384-90. doi: 10.1111/j.1538-7836.2006.02153.x. Epub 2006 Aug 1.


Background: Patients undergoing major abdominal surgery carry a high risk of venous thromboembolism (VTE), but the optimal duration of postoperative thromboprophylaxis is unknown.

Objectives: To evaluate the efficacy and safety of thromboprophylaxis with the low molecular weight heparin (dalteparin), administered for 28 days after major abdominal surgery compared to 7 days' treatment.

Patients/methods: A multicenter, prospective, assessor-blinded, open-label, randomized trial was performed in order to evaluate prolonged thromboprophylaxis after major abdominal surgery. In total, 590 patients were recruited, of whom 427 were randomized and received at least 1 day of study medication, and 343 reached an evaluable endpoint. The primary efficacy endpoint was objectively verified VTE occurring between 7 and 28 days after surgery. All patients underwent bilateral venography at day 28.

Results: The cumulative incidence of VTE was reduced from 16.3% with short-term thromboprophylaxis (29/178 patients) to 7.3% after prolonged thromboprophylaxis (12/165) (relative risk reduction 55%; 95% confidence interval 15-76; P=0.012). The number that needed to be treated to prevent one case of VTE was 12 (95% confidence interval 7-44). Bleeding events were not increased with prolonged compared with short-term thromboprophylaxis.

Conclusions: Four-week administration of dalteparin, 5000 IU once daily, after major abdominal surgery significantly reduces the rate of VTE, without increasing the risk of bleeding, compared with 1 week of thromboprophylaxis.

Publication types

  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abdomen / surgery
  • Adult
  • Aged
  • Aged, 80 and over
  • Anticoagulants / administration & dosage*
  • Anticoagulants / adverse effects
  • Dalteparin / administration & dosage*
  • Dalteparin / adverse effects
  • Female
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Postoperative Complications / epidemiology
  • Postoperative Complications / prevention & control*
  • Prospective Studies
  • Risk Factors
  • Thromboembolism / epidemiology
  • Thromboembolism / etiology
  • Thromboembolism / prevention & control*
  • Time Factors


  • Anticoagulants
  • Dalteparin