Fillers POEM

Fondaparinux is as effective and safe as unfractionated heparin for pulmonary embolism

BMJ 2004; 328 doi: (Published 04 March 2004) Cite this as: BMJ 2004;328:0-f

Question Is fondaparinux as safe and effective as unfractionated heparin for treating pulmonary embolism?

Synopsis Fondaparinux (Arixtra) is an inhibitor of factor Xa. Although it's not a low molecular weight heparin, it's similar in that it's given by subcutaneous injection and does not require monitoring of anticoagulation. Alternatives to unfractionated heparin are widely used for treating deep vein thrombosis, but they are less widely used for pulmonary embolism because of concerns about efficacy. In the current randomised controlled trial (non-blinded), 2213 adults with a pulmonary embolism were randomised to either unfractionated heparin titrated to an activated partial thromboplastin time between 1.5 and 2.5 or fondaparinux given by subcutaneous injection. The average age was 62 years and 55% were women. Randomisation and allocation concealment were appropriate, groups were similar at baseline, analysis was by intention to treat, and outcomes were reviewed (although not initially assigned) by a blinded monitoring committee. Fondaparinux was given as a single daily injection of 5 mg for patients weighing less than 50 kg, 7.5 mg if they weighed between 50 and 100 kg, and 10 mg if they were heavier than 100 kg. Patients were started on warfarin as soon as possible and treatment with unfractionated heparin or fondaparinux continued for five days and until warfarin was therapeutic for at least two days. Patients were followed up for three months; the primary outcome was recurrence of venous thromboembolism. At the end of the study period, there was no significant difference in any of the primary or secondary outcomes: recurrent venous thromboembolism (3.8% for fondaparinux v 5.0% for unfractionated heparin), major bleeding (2.0% v 2.4%), non-major bleeding (5.7% v 8.4%), and death (5.2% v 4.4%). One in seven patients treated with fondaparinux were treated as outpatients for at least part of the time, the majority for at least three days. This was an industry sponsored trial, and four of the authors are employees of the company that makes fondaparinux.

Bottom line Fondaparinux is similar in effectiveness and safety to unfractionated heparin in treating pulmonary embolism. Although more expensive, it offers the advantage of dosing without attention to the extent of coagulation, and offers the possibility of outpatient treatment for selected patients.

Level of evidence 1b (see Individual randomised controlled trials (with narrow confidence interval)

Matisse Investigators. Subcutaneous fondaparinux versus intravenous unfractionated heparin in the initial treatment of pulmonary embolism. N Engl J Med 2003;349: 1695-702.

©infoPOEMs 1992-2003


  • Patient-Oriented Evidence that Matters. See editorial (BMJ 2002;325: 983)

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