Abstract 98: Direct-Acting Oral Anticoagulants and Antiseizure Medications for Atrial Fibrillation and Epilepsy: Risk of Thromboembolic and Major Bleeding Events

Abstract

Rationale: Direct-acting oral anticoagulants (DOACs) are commonly prescribed with antiseizure medications (ASMs) due to concurrency and causal links between atrial fibrillation (AF) and epilepsy. However, enzyme-inducing-ASMs (EI-ASMs) may reduce absorption and accelerate metabolism of DOACs, potentially lowering DOAC levels and elevating thromboembolism risk. Methods: We leveraged large-scale healthcare data to conduct an emulated target trial among a nationally representative cohort with AF and epilepsy. Thromboembolic and bleeding event rates were contrasted between adults on DOACs + EI-ASMs versus active comparators on DOACs + non-enzyme inducing ASMs. Data-adaptive high-dimensional propensity score matching was employed to control for observed confounders and proxies for unobserved confounders. Adjusted hazard ratios (aHRs) were estimated using Cox proportional hazard models with robust variance estimators to account for clustering within matched pairs. Results: Among incident ASM + DOAC users, we identified 14,078 and 14,158 episodes that met eligibility criteria for assessment of thromboembolic and bleeding outcomes, respectively. Incidence per 1,000 person-years was 88.5 for thromboembolic events and 68.3 for major bleeding events. Compared with use of non-enzyme inducing ASMs, use of EI-ASMs with DOACs was not associated with a difference in thromboembolic events (aHR=1.10, 95% CI: 0.82-1.46), but was associated with a reduction in major bleeding events (aHR=0.63, 95% CI: 0.44-0.89). Conclusions: EI-ASMs were not associated with alteration in DOAC efficacy. These real-world data are reassuring for the care of adults with epilepsy who require anticoagulation, particularly across a larger global community where EI-ASMs remain mainstays. Further research is needed on the reduction in bleeding risk with EI-ASMs, as this may be suggestive of pharmacokinetic interactions lowering DOAC levels without negating therapeutic effects.