Warfarin with a target INR of 1.6-2.6 in Japanese patients with NVAF was associated with lower thromboembolic events compared to no warfarin (1.3-1.5% vs 3.0%; P=0.0059).
Cohort (n=7,527)
Does warfarin at specific target INR levels prevent thromboembolic events without excessive hemorrhage in Japanese patients with non-valvular atrial fibrillation?
In Japanese patients with non-valvular atrial fibrillation, an INR of 1.6-2.6 is safe and effective for preventing thromboembolic events, while higher INRs increase the risk of major hemorrhage.
p-value: p=0.0059
BACKGROUND: Target anticoagulation levels for warfarin in Japanese patients with non-valvular atrial fibrillation (NVAF) are unclear. METHODS AND RESULTS: Of 7,527 patients with NVAF, 1,002 did not receive warfarin (non-warfarin group), and the remaining patients receiving warfarin were divided into 5 groups based on their baseline international normalized ratio (INR) of prothrombin time (≤1.59, 1.6-1.99, 2.0-2.59, 2.6-2.99, and ≥3.0). Patients were followed-up prospectively for 2 years. Primary endpoints were thromboembolic events (cerebral infarction, transient ischemic attack, and systemic embolism), and major hemorrhage requiring hospital admission. During the follow-up period, thromboembolic events occurred in 3.0% of non-warfarin group, but at lower frequencies in the warfarin groups (2.0, 1.3, 1.5, 0.6, and 1.8%/2 years for INR values of ≤1.59, 1.6-1.99, 2.0-2.59, 2.6-2.99, and ≥3.0, respectively; P=0.0059). Major hemorrhage occurred more frequently in warfarin groups (1.5, 1.8, 2.4, 3.3, and 4.1% for INR values ≤1.59, 1.6-1.99, 2.0-2.59, 2.6-2.99, and ≥3.0, respectively; P=0.0041) than in non-warfarin group (0.8%/2 years). These trends were maintained when the analyses were confined to patients aged ≥70 years. CONCLUSIONS: An INR of 1.6-2.6 is safe and effective at preventing thromboembolic events in patients with NVAF, particularly patients aged ≥70 years. An INR of 2.6-2.99 is also effective, but associated with a slightly increased risk in major hemorrhage. (UMIN Clinical Trials Registry UMIN000001569)
Inoue et al. (Tue,) conducted a cohort in Non-valvular atrial fibrillation (NVAF) (n=7,527). Warfarin vs. No warfarin was evaluated on Thromboembolic events (cerebral infarction, transient ischemic attack, and systemic embolism), and major hemorrhage requiring hospital admission (p=0.0059). Warfarin with a target INR of 1.6-2.6 in Japanese patients with NVAF was associated with lower thromboembolic events compared to no warfarin (1.3-1.5% vs 3.0%; P=0.0059).
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