For patients with nonvalvular atrial fibrillation (NVAF) receiving warfarin therapy, the target international normalized ratio range of 2.0 to 3.0 is recommended by Western countries. However, this treatment carries a higher risk of bleeding which suggests more researches on whether low-intensity warfarin therapy (range <2.0 to 3.0) is suitable for East Asian patients. Three databases were searched from inception to April 21, 2016. Studies that reported thromboembolic and hemorrhagic events in low- and standard-intensity warfarin groups were included. Finally, seven studies were included in the analysis. There was a significantly decreased risk of hemorrhagic events (odds ratio [OR] 0.59, 95% confidence interval [CI] 0.43 to 0.82, p = 0.002) with no statistically increased risk of thromboembolic events (OR 1.14, 95% CI 0.80 to 1.62, p = 0.47) in the 1.5 to 2.0 group compared with that of the 2.0 to 3.0 group. Meanwhile, there was no significant difference of cardiovascular mortality (OR 1.58, 95% CI 0.89 to 2.83, p = 0.12) between the 2 groups. Further analysis showed there was no significance in thromboembolic events (OR 1.15, 95% CI 0.83 to 1.60, p = 0.40), major bleeding events (OR 0.74, 95% CI 0.50 to 1.09, p = 0.13), and cardiovascular mortality (OR 1.45, 95% CI 0.79 to 2.65, p = 0.23) between 1.5 to 2.5 and 2.0 to 3.0 groups. Although no significant difference was found in hemorrhagic events (OR 0.76, 95% CI 0.57 to 1.01, p = 0.06), there was a decreased trend in it. In conclusion, low-intensity warfarin therapy can achieve reduced hemorrhage without increasing thromboembolism for East Asian patients with NVAF receiving warfarin therapy.
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