Journal of Thrombosis and Thrombolysis

, Volume 46, Issue 4, pp 461–465 | Cite as

Warfarin control in patients transitioning to warfarin after non-vitamin K oral anticoagulant (NOAC) therapy

  • Nijole BernaitisEmail author
  • Tony Badrick
  • Andrew K. Davey
  • Julia Crilly
  • Shailendra Anoopkumar-Dukie


Warfarin has long been the most widely prescribed oral anticoagulant. Introduction of non-vitamin K oral anticoagulants (NOACs) has provided anticoagulant options but also presented the potential challenge of transitioning between agents. Changes from NOACs to warfarin are particularly problematic with delays to therapeutic effect and limited real-world data regarding the impact on warfarin control. The aim of this study was to investigate the frequency of switching anticoagulants and the effect on warfarin control. Retrospective data was collected for patients at a warfarin program in Queensland Australia who had exited the program for NOACs plus those who had reverted to warfarin. Data included documented reasons for change and International Normalised Ratio (INR) results with time in therapeutic range (TTR) calculated as a measure of warfarin control. Over 5 years, a total of 3036 patients ceased warfarin to commence a NOAC but 142 (4.7%) reverted to warfarin. Majority of patients (60.6%) reverted to warfarin within 6 months of trialling NOACs with a median of 6 days to therapeutic INR. There was no significant difference in warfarin control before changing to NOACs and after reverting to warfarin (mean TTR 75%) but significantly more frequent testing and lower doses were required to achieve this control. Transitions from warfarin to NOACs results in almost a week to therapeutic effect and warfarin therapy may be further complicated by a need for increased frequency of testing. Further studies are required to refine transition strategies particularly from warfarin to NOAC and minimise potential risks to patients.


Anticoagulant International normalized ratio Warfarin 


Compliance with ethical standards

Conflict of interest

Nijole Bernaitis declares that she has no conflict of interest. Tony Badrick declares that he has no conflict of interest. Andrew K. Davey declares that he has no conflict of interest. Julia Crilly declares that she has no conflict of interest. Shailendra Anoopkumar-Dukie declares that he has no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

This study was a retrospective data analysis which met the conditions for a waiver of consent.


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© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Quality Use of Medicines NetworkGriffith UniversitySouthportAustralia
  2. 2.School of Pharmacy & PharmacologyGriffith UniversitySouthportAustralia
  3. 3.The Royal College of Pathologists of Australasia (RCPA) Quality Assurance ProgramsSt LeonardsAustralia
  4. 4.Department of Emergency MedicineGold Coast HealthSouthportAustralia

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