Warfarin Institute of America

Dedicated To Your Health

There were two studies published in 2003 regarding the efficacy of low intensity warfarin therapy. The first study, PREVENT, was published in the New England Journal of Medicine on April 10, 2003, by PM Ridker, et al. This study was a randomized, double-blind, placebo-controlled trial. The study followed 508 patients for an average of 4.3 years. Patients enrolled in the study were randomized to either low intensity warfarin therapy (INR=1.5-2.0) or placebo, after completing at least 3 months of treatment with conventional intensity warfarin (INR=2.0-3.0). The study’s primary end-points were recurrent venous thromboembolism (VTE), major hemorrhage, and death. The results of the study revealed that low dose warfarin was significantly more effective than placebo at preventing a recurrent VTE. There were more reports of minor bleeding among patients randomized to the warfarin group than the placebo group; however, there was not a significant difference in major bleeding events between the two groups. The authors did not find a statistical difference in the number of deaths between the two groups studied. Two important things to consider regarding the results of this study include: (1) this data is only valid for recurrent VTE; and (2) this study excluded patients with antiphospholipid antibodies and systemic lupus erythematosus (SLE). The second study, ELATE, was published in the New England Journal of Medicine on August 14, 2003, by C. Kearon, et al. This study was a multi-center, randomized, double-blind comparison of conventional intensity warfarin therapy (INR=2.0-3.0) to low intensity warfarin therapy (INR=1.5-1.9). There were 738 patients followed for an average of 2.4 years. The primary outcomes of the ELATE study include recurrent VTE, bleeding (major and minor), and death. The results of this study showed that conventional intensity warfarin therapy is more effective than low intensity warfarin therapy for prevention of recurrent VTE without an increased risk of bleeding. There was not a statistical difference in number of deaths between the two groups. Again, with this study it is important to consider that these results are applicable only to prevention of recurrent VTE and that patients with antiphospholipid antibodies were excluded. In summary, the results of the PREVENT and ELATE studies are consistent with previously published trials which evaluated long-term VTE prophylaxis. The overall risk reduction with low dose warfarin therapy is 75%¹, while conventional intensity warfarin therapy results in more than a 90%^2,3,4 reduction in recurrent thrombosis risk.

EDITOR'S NOTE:  Occasionally there surfaces another paper advocating using a 1 mg dose of warfarin and no monitoring.  I have done over 30,000 patient visits and have seen several people who need much less than 1 mg per day.  One went as low as 3 mg/wk.  This meant that he would have a high INR if he took as little as 1/2 of a 1 mg warfarin tablet daily.  I cannot figure how anyone would be justified in advocating any warfarin dose as needing no monitoring.

1. Ridker PM, Goldhaber SZ, Danielson E, et al. Long-term, low-intensity warfarin therapy for the prevention of recurrent venous thromboembolism. N Engl J Med 2003;348:1425-34.

2. Kearon C, Ginsberg JS, Kovacs MJ, et al. Comparison of low-intensity warfarin therapy with conventional-intensity warfarin therapy for long-term prevention of recurrent venous thromboembolism. N Engl J Med 2003;349:631-9.

3. Prins MH, Hutten BA, Koopman MM, Büller HR. Long-term treatment of venous thromboembolic disease. Thromb Haemost 1999;82:892-8.

4. Schulman S, Granqvist S, Holmström M, et al. The duration of oral anticoagulant therapy after a second episode of venous thromboembolism. N Engl J Med 1997;336:393-8.

© 2004 Sunset Andersen   Used by permission

© 2004 - 2006 Lodwick Creations, LLC

SEE A CATALOG OF PUBLICATIONS AVAILABLE FROM LODWICK CREATIONS, LLC.

LEARN HOW YOU CAN BECOME LISTED ON THE HONOR ROLL OF SUPPORTERS AND TAKE ADVANTAGE OF THE BENEFITS

REQUEST A MEDICATION CONSULTATION

CHECK OUR LINE OF "HAD YOUR RAT POISON TODAY?" MERCHANDISE

DONATE USING PAYPAL

Home                              Back to interactions list

Contact Mr. Lodwick at allodwick@earthlink.net

Last updated January 2, 2006