Comparisons between Oral Anticoagulants among Older Nonvalvular Atrial Fibrillation Patients

Abstract

OBJECTIVES: Older adult patients are underrepresented in clinical trials comparing non–vitamin K antagonist oral anticoagulants (NOACs) and warfarin. This subgroup analysis of the ARISTOPHANES study used multiple data sources to compare the risk of stroke/systemic embolism (SE) and major bleeding (MB) among very old patients with nonvalvular atrial fibrillation (NVAF) prescribed NOACs or warfarin. DESIGN: Retrospective observational study. SETTING: The Centers for Medicare & Medicaid Services and three US commercial claims databases. PARTICIPANTS: A total of 88 582 very old (aged ≥80 y) NVAF patients newly initiating apixaban, dabigatran, rivaroxaban, or warfarin from January 1, 2013, to September 30, 2015. MEASUREMENTS: In each database, six 1:1 propensity score matched (PSM) cohorts were created for each drug comparison. Patient cohorts were pooled from all four databases after PSM. Cox proportional hazards models were used to estimate hazard ratios (HRs) of stroke/SE and MB. RESULTS: The patients in the six matched cohorts had a mean follow-up time of 7 to 9 months. Compared with warfarin, apixaban (HR =.58; 95% confidence interval [CI] =.49-.69), dabigatran (HR =.77; 95% CI =.60-.99), and rivaroxaban (HR =.74; 95% CI =.65-.85) were associated with lower risks of stroke/SE. For MB, apixaban (HR =.60; 95% CI =.54-.67) was associated with a lower risk; dabigatran (HR =.92; 95% CI =.78-1.07) was associated with a similar risk, and rivaroxaban (HR = 1.16; 95% CI = 1.07-1.24) was associated with a higher risk compared with warfarin. Apixaban was associated with a lower risk of stroke/SE and MB compared with dabigatran (stroke/SE: HR =.65; 95% CI =.47-.89; MB: HR =.60; 95% CI =.49-.73) and rivaroxaban (stroke/SE: HR =.72; 95% CI =.59-.86; MB: HR =.50; 95% CI =.45-.55). Dabigatran was associated with a lower risk of MB (HR =.77; 95% CI =.67-.90) compared with rivaroxaban. CONCLUSION: Among very old NVAF patients, NOACs were associated with lower rates of stroke/SE and varying rates of MB compared with warfarin. J Am Geriatr Soc 67:1662–1671, 2019.