Use of oral anticoagulation therapy in the first 3 months after the diagnosis of atrial fibrillation in Israel: A population-based study

Introduction: Oral anticoagulation (OAC) therapy reduces the risk of ischemic stroke in patients with atrial fibrillation (AF) while increasing the risk of bleeding. Recently, non-vitamin K antagonist oral anticoagulants (NOACs) have become available with lower rates of intracranial bleeding, and some of them have presented a reduced risk of major bleeding. The purpose of this study is to evaluate the change in purchasing patterns of OACs (both warfarin and NOACs) over time in patients with AF according to stroke and bleeding risk, in the first 3 months after diagnosis. Methods and Results: We conducted a historical cohort study using the Clalit Health Services electronic medical records database. The study population included all members aged ≥21 years, with a new diagnosis of nonvalvular AF between 2008 and 2015. A total of 58 385 cases were identified. The mean age was 73.1 (±14.1) years, and 52.3% of the patients were women. The median CHA₂DS₂-VASc score was 4 (interquartile range, 3-5). OACs were purchased by 19 705 patients (33.8%) within the first 3 months of first diagnosis of AF, with patients at higher embolic risk as stratified by the CHA₂DS₂-VASc score and having higher purchasing rates (37.1%). Between 2008 and 2010, 29% of patients purchased a vitamin K antagonist, the only available OAC at the time. OAC purchasing increased to 41.4% between 2014 and 2015, with half of the patients purchasing an NOAC. Conclusion: In this real-world, population-based cohort study of patients with newly diagnosed AF, we found a lower than expected rate of OAC prescription within 3 months of diagnosis but an encouraging increase in OAC purchasing over time. The use of NOACs has risen exponentially within just a few years, accounting for a greater pool of patients with being prescribed an OAC.