Ischemic stroke and systemic embolism among patients with non-valvular atrial fibrillation who abandon oral anticoagulant therapy.

Objectives: To compare the risk of stroke and systemic embolism (SE) among patients with nonvalvular atrial fibrillation (NVAF) who abandoned their first direct oral anticoagulant (DOAC) fill ("abandoners") relative to patients who continued DOACs beyond the first fill ("continuers").
Methods: In this retrospective longitudinal study, adults with NVAF prescribed DOACs were selected from Symphony Health, an ICON plc Company, PatientSource, 1 April 2017 to 31 October 2020. A 90-day landmark period following the first DOAC fill was used to classify patients as abandoners or continuers. Inverse probability of treatment weighting was used to balance baseline characteristics between cohorts. Time to ischemic stroke/SE was described and compared between cohorts using weighted Kaplan-Meier and Cox proportional hazard models from the end of the landmark period until end of clinical activity or data.
Results: After weighting, 200,398 and 211,352 patients comprised the abandoner and continuer cohorts, respectively. The mean duration of follow-up was 14.9 and 15.7 months, respectively. At 12 months of follow-up, the probability of ischemic stroke/SE was 1.34% in the abandoner cohort and 1.00% in the continuer cohort; the risk of ischemic stroke/SE was 35% higher in the abandoner versus continuer cohort (hazard ratio [95% confidence interval] = 1.35 [1.20, 1.51]; p  < 0.0001).
Conclusions: Patients with NVAF who abandoned the first DOAC fill had significantly higher risk of ischemic stroke/SE compared to patients who continued therapy beyond the first fill. There is an unmet need for better access to DOACs so that the long-term risk of poor outcomes may be minimized.