A comparison of three months of anticoagulation with extended anticoagulation for a first episode of idiopathic venous thromboembolism
CommentThis well-designed study of anticoagulation in patients with idiopathic thromboembolism demonstrated a very marked reduction in events among patients whose anticoagulation was extended beyond three months.
As the authors note, their study does not provide evidence for the optimal duration of treatment of these patients. At 12 months follow-up, there were only 61 patients left in the study, from the original 162. Looking at the cumulative probability curves for recurrence (shown in the article), it would appear that the benefit extended to at least 6 months.
These results cannot be extrapolated directly to patients who have a thromboembolic event secondary to a defined, transient or modifiable risk factor (such as surgery, trauma, bedrest), in whom the removal of the risk factor would be expected to lower the risk of recurrence in the absence of anticoagulation.
Whether or not anticoagulation at a lower INR would also be effective is an important question that needs to be addressed in further studies. Lower levels of anticoagulation have been disappointing in the treatment of atrial fibrillation, but venous thromboembolism is a different disorder from atrial thromboembolism.
June 9, 1999
ReferencesReferences related to this article from the NLM's PubMed database.
August 12, 1999
Letters to the editor about this article, in the August 12 NEJM. Does anticoagulation reduce or merely delay recurrent thrombosis? Optimum duration of treatment?
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