Clinical question: Is dalteparin better than unfractionated heparin at preventing venous thromboembolism (VTE) in ICU patients?
Background: VTE is an important health problem for critically ill patients, but prevention is possible, with both unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) superior to placebo in previous studies. Studies comparing UFH and LMWH in ICU patients have been inconclusive thus far.
Study design: Randomized controlled trial.
Setting: Sixty-seven ICUs in six countries from 2006 to 2010.
Synopsis: Researchers randomized 3,746 patients who met the enrollment criteria to either the LMWH dalteparin 5,000 units daily or UFH 5,000 IU twice daily. The drug was held if major bleeding occurred or the patient developed thrombocytopenia concerning heparin-induced thrombocytopenia (HIT). Patients were followed until discharge or death. VTE was evaluated by ultrasound two days after ICU admission and then twice weekly.
There was no difference in incidence of VTE in patients receiving dalteparin versus UFH [5.1% vs. 5.8%, HR 0.92 (CI 0.68-1.23), P=0.57]. Fewer pulmonary emboli occurred in the dalteparin group (1.3% vs. 2.3%, HR 0.51, P=0.01). There was no difference in major bleeding or HIT between groups.
Bottom line: Dalteparin and UFH were equally effective at preventing proximal VTE in ICU patients, but dalteparin prevented more pulmonary emboli.
Citation: The PROTECT investigators for the Canadian Critical Care Trials Group and the Australian and New Zealand Intensive Care Society Clinical Trials Group. Dalteparin versus unfractionated heparin in critically ill patients. N Engl J Med. 2010;364(14):1305-1314.
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