Article Text

other Versions

Original article
Impact of provision of time in therapeutic range value on anticoagulation management in atrial fibrillation patients on warfarin
  1. Duo Huang1,
  2. Chi-Lap Wong2,
  3. Kwan-Wa Cheng2,
  4. Pak-Hei Chan1,
  5. Wen-Sheng Yue3,
  6. Chun-Ka Wong1,
  7. Chi-Wai Ho1,
  8. Ian C K Wong2,
  9. Esther W Chan2,
  10. Chung Wah Siu1
  1. 1Cardiology Division, Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
  2. 2Department of Pharmacology and Pharmacy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
  3. 3Affiliated Hospital of North Sichuan Medical College and Medical Imaging Key Laboratory, Nanchong, China
  1. Correspondence to Professor Chung Wah Siu, Cardiology Division, Department of Medicine, The University of Hong Kong, Hong Kong SAR 999077, China; cwdsiu{at}


Introduction The importance of time in therapeutic range (TTR) in patients prescribed warfarin therapy for stroke prevention in atrial fibrillation (AF) cannot be overemphasised.

Aim To evaluate the impact of provision of TTR results during clinic visits on anticoagulation management.

Design Single-centred, randomised controlled study.

Setting Fifteen arrhythmia clinics in Hong Kong.

Patients AF patients prescribed warfarin.

Interventions Provision of TTR or no provision of TTR.

Main outcome measures A documented discussion between doctors and patients about switching warfarin to a non-vitamin K oral anticoagulant (NOAC).

Results Four hundred and eighty one patients with AF prescribed warfarin were randomly assigned to (1) a TTR provision group or (2) control. Their mean age was 73.6±12.0 years and 60.7% were men. The mean CHA2DS2-VASc score was 3.2±1.6 and the mean HASBLED score was 1.7±1.2. The mean TTR was 63.9%±29.9%. At the index clinic visit, 71 of 481 patients (14.8%) had a documented discussion about switching warfarin to a NOAC. Patients with provision of TTR results were more likely to discuss switching warfarin to a NOAC than controls (19.1% vs 10.6%, P=0.03), especially those with a TTR <65% (35.2% vs 10.6%, P<0.001). A higher proportion of patients with provision of TTR results switched to a NOAC (5.9% vs 4.1%, P=0.49).

Conclusions The provision of TTR among patients on warfarin was associated with a discussion about switching from warfarin to a NOAC in those with TTR <65%, but did not result in actual switching to a NOAC, suggesting additional barriers.

  • time in therapeutic range
  • international normalized ratio
  • atrial fibrillation
  • warfarin
  • non-vitamin K oral anticoagulants

Statistics from


  • Contributors DH, EWC, CWS: conceived and designed the project; DH, C-LW, K-WC, P-HC, W-SY, C-KW, C-WH, ICKW, EWC, CWS: carried out the project; DH, EWC, CWS: analyzed the data; DH, C-LW, EWC, CWS: contributed materials/analysis tools; DH, C-LW, K-WC, P-HC, W-SY, C-KW, C-WH, ICKW, EWC, CWS: wrote the paper.

  • Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval Institutional Ethics Review Board of the University of Hong Kong.

  • Provenance and peer review Not commissioned; externally peer reviewed.

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.