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Subcutaneous Unfractionated vs. Low-Molecular-Weight Heparin in Venous Thromboembolism

Weight-adjusted dosing of subcutaneous unfractionated heparin is as effective and safe as low-molecular-weight heparin.

During the past decade, therapy for venous thromboembolism (VTE) has shifted from intravenous unfractionated heparin to subcutaneous low-molecular-weight heparin (LMWH), which does not require laboratory monitoring and can be given in outpatient settings. However, a few previous studies have suggested that weight-adjusted subcutaneous unfractionated heparin may also be effective.

In this open-label, but rater-blinded, trial in Canada and New Zealand, researchers randomized 708 adults with VTE to one of two treatments — weight-adjusted subcutaneous unfractionated heparin without APTT monitoring (initial dose 333 U/kg, followed by 250 U/kg every 12 hours) or LMWH (100 IU/kg every 12 hours). These treatments were continued for at least 5 days and until warfarin therapy had achieved an INR of 2.0 or higher. Eighty-one percent of patients had deep venous thrombosis alone, and 19% had symptomatic pulmonary embolism.

There was no significant difference between groups in rates of recurrent VTE at 3 months (about 3.5%) or in major bleeding complications at 10 days (about 1%). Approximately 70% of both groups were treated entirely on an outpatient basis.

Comment: These findings indicate that weight-adjusted unfractionated heparin — administered subcutaneously and without APTT monitoring — is as safe and effective as LMWH, at far lower cost (US$40 vs. $700 for medication). Nevertheless, an editorialist calls for a fully blinded replication of the data before the approach can be recommended clinically.

— Thomas L. Schwenk, MD

Published in Journal Watch General Medicine September 21, 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 23/30; 296:935-42.

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• Medline abstract (Free)

Carson JL. Subcutaneous unfractionated heparin vs low-molecular-weight heparin for acute thromboembolic disease: Issues of efficacy and cost. JAMA 2006 Aug 23/30; 296:991-3.

• Original article (Subscription may be required)
• Medline abstract (Free)