BACKGROUND: The perceived risk of serious bleeding is an obstacle to the use of 
oral anticoagulation in East Asia. The efficacy and safety of apixaban in East 
Asian patients with atrial fibrillation are unknown.
METHODS: ARISTOTLE included 18,201 patients with nonvalvular atrial fibrillation 
randomized to apixaban 5mg twice daily or warfarin. The efficacy and safety of 
apixaban and warfarin among patients recruited from East Asia (n = 1,993) were 
compared with those recruited from outside East Asia (n = 16,208).
RESULTS: Compared with warfarin, apixaban resulted in a consistent reduction in 
stroke or systemic embolism in East Asian (hazard ratio [HR] 0.74, 95% CI 
0.50-1.10) and non-East Asian (HR 0.81, 95% CI 0.66-0.99) patients (interaction 
P = .70). Consistent benefits of apixaban over warfarin were also seen for major 
bleeding in East Asian (HR 0.53, 95% CI 0.35-0.80) and non-East Asian (HR 0.72, 
95% CI 0.62-0.83) patients (interaction P = .17). There was a greater reduction 
in major or clinically relevant nonmajor bleeding with apixaban compared with 
warfarin in East Asian (HR 0.49, 95% CI 0.35-0.67) than in non-East Asian (HR 
0.71, 95% CI 0.63-0.79) patients (interaction P = .03). Numerically higher rates 
of intracranial bleeding were seen in East Asian patients with warfarin but not 
with apixaban.
CONCLUSIONS: Apixaban resulted in similar reductions in stroke or systemic 
embolism and major bleeding and greater reductions in major or clinically 
relevant nonmajor bleeding in patients from East Asia. Warfarin is associated 
with more intracranial bleeding, particularly in patients from East Asia.