March 18, 2019PLoS ONEOpen Access

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

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Why the study?

It was unknown whether NOAC is superior to warfarin with good time in therapeutic range based on a lower INR target of 1.5-2.5 among Asians with NVAF.

Does NOAC therapy improve composite outcomes compared to well-managed warfarin with a lower INR target of 1.5-2.5 in Asian patients with non-valvular atrial fibrillation?

Structured PICO

Does NOAC therapy improve composite outcomes compared to well-managed warfarin with a lower INR target of 1.5-2.5 in Asian patients with non-valvular atrial fibrillation?

Population

18,491 Asian patients with non-valvular atrial fibrillation (NVAF) from the Taiwan Chang Gung Memorial Hospital Database (n=3,396 NOAC, n=5,197 warfarin, n=9,898 no-treatment). Excluded: venous thromboembolism, valvular atrial fibrillation, or joint replacement therapy within 6 months.

Intervention

Non-vitamin K antagonist oral anticoagulants (NOACs) including dabigatran, rivaroxaban, or apixaban (79.2% on low-dose NOACs)

Comparator

Well-managed warfarin with a lower INR target of 1.5 to 2.5 (artificial time in therapeutic range [aTTR] >70%) and no-treatment

Outcome

Composite outcome defined as the summation of all efficacy outcomes (ischemic stroke, systemic embolism, acute myocardial infarction, and mortality) and safety outcomes (intracranial hemorrhage, gastrointestinal bleeding, and other critical site bleeding)composite

Implication

Supports NOAC equivalence to optimized low-target warfarin in Asian NVAF; leaves open need for randomized confirmation before practice change.

Abstract

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.