Randomized Trial of Warfarin Nomograms
Authors: Kenneth L. McCall
Journal: Annals of Internal Medicine (2004)

Letters16 March 2004Randomized Trial of Warfarin NomogramsKenneth L. McCall, PharmD, BCPS, CACPKenneth L. McCall, PharmD, BCPS, CACPFrom Texas Tech School of Pharmacy, Amarillo, TX 79106.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-140-6-200403160-00029 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail TO THE EDITOR:Kovacs and colleagues (1) did not discuss the lack of reliability of the INR during the onset of warfarin therapy. The omission of this information is crucial because Kovacs and colleagues' study was not powered to detect clinically meaningful outcomes such as recurrent venous thromboembolism or major hemorrhagic events.The INR system does not correlate with the antithrombotic activity of warfarin during the initiation phase because the prolongation of the prothrombin time during warfarin induction primarily reflects the depletion of factor VII (2, 3). However, the ability of warfarin to block tissue factor–induced coagulation in animal models ...References1. Kovacs MJ, Rodger M, Anderson DR, Morrow B, Kells G, Kovacs J, et al . Comparison of 10-mg and 5-mg warfarin initiation nomograms together with low-molecular-weight heparin for outpatient treatment of acute venous thromboembolism. A randomized, double-blind, controlled trial. Ann Intern Med. 2003;138:714-9. [PMID: 12729425] LinkGoogle Scholar2. Loeliger EA, Van Der Esch B, Mattern MJ, Hemker HC. The biological disappearance rate of prothrombin, factors VII, IX and X from plasma in hypothyroidism, hyperthyroidism, and during fever. Thromb Diath Haemorrh. 1964;10:267-77. [PMID: 14113369] MedlineGoogle Scholar3. Harrison L, Johnston M, Massicotte MP, Crowther M, Moffat K, Hirsh J. Comparison of 5-mg and 10-mg loading doses in initiation of warfarin therapy. Ann Intern Med. 1997;126:133-6. [PMID: 9005747] LinkGoogle Scholar4. Zivelin A, Rao LV, Rapaport SI. Mechanism of the anticoagulant effect of warfarin as evaluated in rabbits by selective depression of individual procoagulant vitamin K-dependent clotting factors. J Clin Invest. 1993;92:2131-40. [PMID: 8227329] CrossrefMedlineGoogle Scholar Author, Article, and Disclosure InformationAffiliations: From Texas Tech School of Pharmacy, Amarillo, TX 79106. PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetailsSee AlsoComparison of 5-mg and 10-mg Loading Doses in Initiation of Warfarin Therapy Linda Harrison , Marilyn Johnston , M. Patricia Massicotte , Mark Crowther , Karen Moffat , and Jack Hirsh Comparison of 10-mg and 5-mg Warfarin Initiation Nomograms Together with Low-Molecular-Weight Heparin for Outpatient Treatment of Acute Venous Thromboembolism Michael J. Kovacs , Marc Rodger , David R. Anderson , Beverly Morrow , Gertrude Kells , Judy Kovacs , Eleanor Boyle , and Philip S. Wells Randomized Trial of Warfarin Nomograms Michael J. Kovacs and Philip S. Wells Randomized Trial of Warfarin Nomograms Gregory M. Peterson and Shane L. Jackson Randomized Trial of Warfarin Nomograms Richard White and William Dager Randomized Trial of Warfarin Nomograms Robert Zeller Randomized Trial of Warfarin Nomograms Brian F. Gage Randomized Trial of Warfarin Nomograms Robert J. DiDomenico Randomized Trial of Warfarin Nomograms Mark A. Crowther , Linda Harrison , and Jack Hirsh Randomized Trial of Warfarin Nomograms Theodore E. Warkentin Metrics Cited ByA 10 mg warfarin initiation nomogram is safe and effective in outpatients starting oral anticoagulant therapy for venous thromboembolism 16 March 2004Volume 140, Issue 6Page: 491KeywordsAnticoagulantsBlood plasmaHeparinInternational normalized ratioOutpatient clinicsPlasma proteinsProthrombin timeRandomized trialsThrombosisVenous thromboembolism ePublished: 16 March 2004 Issue Published: 16 March 2004 CopyrightCopyright © 2004 by American College of Physicians. All Rights Reserved.PDF DownloadLoading ...