Impact of provision of time in therapeutic range value on anticoagulation management in atrial fibrillation patients on warfarin.

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 CHADS-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.