82 The Impact of Stroke Prophylaxis on Clinical Outcomes After US Emergency Department Diagnosis and Discharge for Atrial Fibrillation

Abstract

There is evidence that oral anticoagulation (OAC) reduces stroke and mortality risk in patients with atrial fibrillation (AF); however, the clinical outcomes after a US emergency department (ED) evaluation for AF are unknown. This analysis seeks to determine the impact of early prescribing and long-term compliance of OAC on the rate of ischemic stroke and mortality after an ED evaluation for AF. In this retrospective, Medicare, fee-for-service cohort of beneficiaries age ≥65, discharged from the ED from 2011-2012 with a new diagnosis of AF and no OAC prescription filled in the 90 days prior were included. Patients were stratified by filling of an OAC prescription (by any provider) within 10 days of ED diagnosis (early) versus not, and were considered compliant (≥80% medication possession ratio, MPR) versus non-compliant (<80% MPR) during their entire observed follow-up (time until the end of the study or time until their first event). Ischemic strokes were identified via ICD-9 codes from inpatient claims data and censored to the available data. Patients who had an adverse event before filling their early OAC prescription were excluded from the analysis. Descriptive statistics and Kaplan Meier curves with time to ischemic stroke were generated to compare patients with and without an early OAC. Of 9,139 with a new AF diagnosis, 24.1% were prescribed an early OAC. Patients with an early OAC were more likely to be younger (mean age early OAC 76.5 versus no early OAC 77.5 years), less likely to be female (58.1% versus 64.1%), and have a lower co-morbidity burden (mean Charlson score 2.7 versus 3.1) (all p<0.001). Among patients with early OACs, compliant patients (n=1380) were older (77 versus 75.1 years), female (61.6% versus 52.1%), and higher stroke-risk with CHA2DS2-VASc (3.1 versus 2.7) (all p<0.001). During the study period, there were 133 (1.9%) ischemic stroke events in the group not treated with an early OAC as compared to 14 (1.0%) in the early OAC compliant and 14 (1.7%) in the early OAC non-compliant group (Figure). In the no early OAC group, there were 665 deaths (9.6%), compared to 50 (3.6%) in early OAC compliant versus 33 (4.0%) in early OAC non-compliant. In patients with a new diagnosis of AF, an early OAC in compliant patients may make a long-term impact on clinical outcomes and warrants further investigation in methods to improve early OAC prescribing.