LAUSR

BACKGROUND Stroke prevention in elderly patients with atrial fibrillation (AF) can be challenging, requiring a balance between thromboembolism prevention and serious bleeding. Comparisons of non-vitamin K antagonist oral anticoagulants (NOACs) and warfarin in the elderly, at different age strata (age 65-74, 75-89, ≥90) in the daily practice have not been well described, particularly in Asians. We aimed to assess the clinical outcomes of NOACs compared to warfarin for stroke prevention in elderly patients with AF. METHODS From 2012 to 2015, 64,169 AF patients aged ≥ 65 years who received at least 1 NOAC (dabigatran, rivaroxaban, or apixaban) or warfarin prescription were identified from the Taiwan National Health Insurance Research Database. The risks of ischemic stroke, intra-cranial hemorrhage (ICH), major bleeding, mortality and composite adverse events were compared between NOACs and warfarin in all patients age ≥65 and specifically, with different age strata; that is 65-74 years, 75-89 years and >90 years. RESULTS Overall NOACs were associated with a significantly lower risk of ischemic stroke (adjusted hazard ratio [aHR] 0.869, 95% confidence interval [CI] 0.812-0.931), ICH (aHR 0.524, 95%CI 0.456-0.601), major bleeding (aHR 0.824, 95%CI 0.776-0.875), mortality (aHR 0.511, 95%CI 0.491-0.532) and composite adverse events (aHR 0.646, 95%CI 0.625-0.667) compared to warfarin. There was heterogeneity in treatment effect for NOACs versus warfarin in different age strata, but the results still favored NOACs even among the very elderly (> 90 years). The results were generally consistent with propensity matching analysis. The absolute risk difference and reductions in ICH and composite adverse events with NOAC use were even greater among the elderly compared to warfarin. CONCLUSIONS Compared to warfarin, NOACs were associated with a significantly lower risk of adverse events, with heterogeneity in treatment effects among different age strata. Overall, the clear safety signal in favor of NOACs over warfarin was evident irrespective of age strata, being most marked in the most elderly.