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Previous Volume 349:631-639 August 14, 2003 Number 7 Next

	Full Text PDF PDA Full Text PowerPoint Slide Set Editorial by Büller, H. R. Letters Add to Personal Archive Add to Citation Manager Notify a Friend E-mail When Cited E-mail When Letters Appear PubMed Citation

ABSTRACT

Background Warfarin is very effective in preventing recurrent venous thromboembolism but is also associated with a substantial risk of bleeding. After three months of conventional warfarin therapy, a lower dose of anticoagulant medication may result in less bleeding and still prevent recurrent venous thromboembolism.

Methods We conducted a randomized, double-blind study, in which 738 patients who had completed three or more months of warfarin therapy for unprovoked venous thromboembolism were randomly assigned to continue warfarin therapy with a target international normalized ratio (INR) of 2.0 to 3.0 (conventional intensity) or a target INR of 1.5 to 1.9 (low intensity). Patients were followed for an average of 2.4 years.

Results Of 369 patients assigned to low-intensity therapy, 16 had recurrent venous thromboembolism (1.9 per 100 person-years), as compared with 6 of 369 assigned to conventional-intensity therapy (0.7 per 100 person-years; hazard ratio, 2.8; 95 percent confidence interval, 1.1 to 7.0). A major bleeding episode occurred in nine patients assigned to low-intensity therapy (1.1 events per 100 person-years) and eight patients assigned to conventional-intensity therapy (0.9 event per 100 person-years; hazard ratio, 1.2; 95 percent confidence interval, 0.4 to 3.0). There was no significant difference in the frequency of overall bleeding between the two groups (hazard ratio, 1.3; 95 percent confidence interval, 0.8 to 2.1).

Conclusions Conventional-intensity warfarin therapy is more effective than low-intensity warfarin therapy for the long-term prevention of recurrent venous thromboembolism. The low-intensity warfarin regimen does not reduce the risk of clinically important bleeding.

Source Information

From McMaster University, Hamilton, Ont. (C.K., J.S.G., J.A.J., B.M., J.I.W., M.A.C., A.G.T., M.G.); the Henderson Research Centre, Hamilton, Ont. (C.K., J.S.G., J.A.J., B.M., J.I.W., M.G.); the University of Western Ontario, London (M.J.K.); Dalhousie University, Halifax, N.S. (D.R.A.); the University of Ottawa, Ottawa, Ont. (P.W., M.R.); the University of New Brunswick, St. John (S.D.); the University of Toronto, Toronto (W.G.); McGill University, Montreal (S.S., S.R.K.); the University of Montreal, Montreal (P.N., J.K.); and Laval University, Quebec, Que. (C.D.) — all in Canada; and the University of California, San Francisco (J.H.).

Full Text of this Article

Related Letters:

Low-Intensity versus Conventional-Intensity Warfarin for Prevention of Recurrent Venous Thromboembolism
Huisman M. V., van der Meer F. J.M., van Rooden C. J., Malik V., Kupfer Y., Tessler S., Tran H. A., Brotman D. J., Ridker P. M., Goldhaber S. Z., Glynn R. J., Kearon C., Julian J. A., Ginsberg J. S., Büller H. R., Prins M. H.
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N Engl J Med 2003; 349:2164-2167, Nov 27, 2003. Correspondence

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