The comparison of non-vitamin K antagonist oral anticoagulants versus well-managed warfarin with a lower INR target of 1.5 to 2.5 in Asians patients with non-valvular atrial fibrillation

BACKGROUND: Previous studies indicated low-intensity warfarin (INR target of 1.5–2.5) achieved reduced hemorrhage without increasing thromboembolism for Asians with non-valvular atrial fibrillation (NVAF). Whether non-vitamin K antagonist oral anticoagulant (NOAC) is superior to warfarin with good time in the therapeutic range (TTR) based on lower INR target among Asians with NVAF remains unknown. METHODS: In this retrospective study collected from Taiwan Chang Gung Memorial Hospital Database, there were 5,197, 3,396, and 9,898 consecutive patients taking warfarin, NOAC, and no-treatment, respectively, from January 1, 2000 to December 31, 2015. Propensity-score weighting was used across the study groups. Patients were followed until the first occurrence of study outcome or end date of study. RESULTS: Among those patients taking warfarin, the mean”artificial” TTR (aTTR) based on a lower INR target of 1.5–2.5 was 44.4±33.3%. Total 79.2% (n = 2,690) patients took low-dose NOACs. Patients with aTTR in the range from <30%(34.0%), 30–50%(17.6%), 50–70%(23.5%) to >70%(24.9%) showed decremental risks of efficacy and composite outcome compared with no-treatment. The risk of major bleeding didn’t increase among patients with top aTTR>70% compared to no-treatment. The NOAC group showed a comparable risk of composite outcome to the warfarin subgroup with aTTR of >70% (P = 0.485). The NOAC group had a lower risk of composite outcome than warfarin subgroup with TTR of>70% based on the INR target of 2.0–3.0 (P = 0.004). CONCLUSIONS: NOACs showed a comparable risk of efficacy, safety, and composite outcome to well-managed warfarin based on a lower INR target of 1.5–2.5 in Asians with NVAF taking oral anticoagulants.