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Subcutaneous Unfractionated Heparin Is as Safe and Effective as LMWH for Acute Treatment of Venous Thromboembolism

Can be given on an outpatient basis without coagulation monitoring

Initial treatment for patients with venous thromboembolism usually includes in-hospital administration of intravenous unfractionated heparin (UFH), with frequent monitoring of activated partial thromboplastin time. Low-molecular-weight heparin (LMWH) has been replacing UFH for treatment of certain disease states because it can be administered subcutaneously and without thromboplastin monitoring, thus reducing overall treatment costs. These authors compared the efficacy and safety of fixed-dose, weight-adjusted, subcutaneous UFH and LMWH.

Investigators enrolled 708 patients at six clinical centers in Canada and New Zealand from September 1998 through February 2004. Patients were randomized to receive either UFH at a dose of 333 U/kg initially, followed by 250 U/kg every 12 hours, or LMWH at a dose of 100 IU/kg every 12 hours. Both groups received the study drug for approximately 7 days, along with overlapping warfarin for 3 months. In both groups, 81% of patients had deep venous thrombosis, and 19% had pulmonary embolism.

The incidence of recurrent venous thromboembolism was similar in the UFH and LMWH groups (3.8% and 3.4%, respectively), as was the incidence of major hemorrhage in the first 10 days (1.1% and 1.4%). Treatment was administered entirely on an outpatient basis for 72% of UFH patients and 68% of LMWH patients. Recurrent venous thromboembolism during 3 months of follow-up occurred in none of the 39 patients with a partial thromboplastin time of <60 seconds and in 3.2% of the 158 patients with a time of 60 seconds; the difference was not significant. In the group receiving UFH, major bleeding occurred in none of the 121 patients with a thromboplastin time of >85 seconds and in none of the 76 patients with a time of 85 seconds.

Comment: In the U.S., LMWH is more than 20 times as expensive as UFH. This study indicates that UFH has the same advantages as LMWH in that it can be given on an outpatient basis and without thromboplastin monitoring. Interestingly, in patients treated with UFH, there was no association between low thromboplastin times and recurrent venous thromboembolism or between high thromboplastin times and major bleeding.

— John A. Marx, MD, FAAEM, FACEP

Published in Journal Watch Emergency Medicine October 6, 2006

Citation(s):

Kearon C et al. Comparison of fixed-dose weight-adjusted unfractionated heparin and low-molecular-weight heparin for acute treatment of venous thromboembolism. JAMA 2006 Aug 23; 296:935-42.

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