AIMS: The risk of stroke in patients with atrial fibrillation (AF) increases 
with age. In the ARISTOTLE trial, apixaban when compared with warfarin reduced 
the rate of stroke, death, and bleeding. We evaluated these outcomes in relation 
to patient age.
METHODS AND RESULTS: A total of 18 201 patients with AF and a raised risk of 
stroke were randomized to warfarin or apixaban 5 mg b.d. with dose reduction to 
2.5 mg b.d. or placebo in 831 patients with ≥2 of the following criteria: age 
≥80 years, body weight ≤60 kg, or creatinine ≥133 μmol/L. We used Cox models to 
compare outcomes in relation to patient age during 1.8 years median follow-up. 
Of the trial population, 30% were <65 years, 39% were 65 to <75, and 31% were 
≥75 years. The rates of stroke, all-cause death, and major bleeding were higher 
in the older age groups (P < 0.001 for all). Apixaban was more effective than 
warfarin in preventing stroke and reducing mortality across all age groups, and 
associated with less major bleeding, less total bleeding, and less intracranial 
haemorrhage regardless of age (P interaction >0.11 for all). Results were also 
consistent for the 13% of patients ≥80 years. No significant interaction with 
apixaban dose was found with respect to treatment effect on major outcomes.
CONCLUSION: The benefits of apixaban vs. warfarin were consistent in patients 
with AF regardless of age. Owing to the higher risk at older age, the absolute 
benefits of apixaban were greater in the elderly.