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 CHA(2)DS(2)-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.