March 22nd, 2011
PROTECT Compares Unfractionated Heparin And Dalteparin In Critically Ill Patients
ICU patients are at high risk to develop venous thromboembolism. Published in NEJM, PROTECT (the Prophylaxis for Thromboembolism in Critical Care Trial) compared the effects of the low-molecular-weight heparin dalteparin with unfractionated heparin (UFH) in 3746 critically ill patients.
There was no significant difference between the two groups in the primary outcome of the trial. Proximal leg deep-vein thrombosis occurred in 5.1% of dalteparin-treated patients and 5.8% of UFH-treated patients (dalteparin HR 0.92; CI 0.68-1.23, p=0.57). However, an important secondary endpoint, pulmonary embolism, was significantly lower in the dalteparin group than in the UFH group (1.3% versus 2.3%, HR 0.51, CI 0.30-0.88, p=0.01). There were no significant differences between the groups in the incidence of major bleeding or hospital deaths.
The authors discussed possible reasons for the positive finding for dalteparin in reducing pulmonary embolism: “Possible explanations include embolism from other sites (e.g., upper limbs, pelvis, or distal leg, for which we did not screen), an effect of dalteparin on the propensity of leg thrombi to embolize, new-onset thrombus formation in pulmonary arteries during critical illness, and insensitivity or nonspecificity of proximal ultrasonography in asymptomatic patients.”