Trends over time in oral anticoagulation and stroke rates in atrial fibrillation: A community-based study

Abstract

Objectives: Over the last decade, direct oral anticoagulants (DOAC) have become preferred over warfarin for stroke prevention in atrial fibrillation (AF). The objectives of this study were to quantify the shift over time from warfarin to DOACs and parallel changes in ischemic and hemorrhagic stroke rates in AF.

Materials and methods: This community-based retrospective study was undertaken within a single integrated health care network from 2011 to 2021. Changes over time in warfarin and DOAC use were quantified by year, both overall and stratified by CHA₂DS₂-VASc score. Ischemic and hemorrhagic stroke rate changes over time were evaluated by Poisson regression. Stroke rates were evaluated in different time eras: 2011-2015 and 2016-2021.

Results: Among 31,978 AF patients followed an average of 5.5 years, any OAC use increased from 50.2 % (2011) to 59.4 % (2020) (p < 0.001). Warfarin use decreased from 49.3 % to 30.8 %, while DOAC use increased from 2.0 % to 30.8 % (both p < 0.001). In 2020, patients with CHA₂DS₂-VASc 0-1 and 2-5 were more likely to use DOACs than warfarin (18.6 % vs. 6.7 %; 33.0 % vs. 28.2 %), whereas in CHA₂DS₂-VASc 6-9 DOACs were used less frequently (30.0 % vs. 40.8 %). Ischemic stroke rates significantly increased by 19 % (95 % CI: 7 %, 32 %) from 2011 to 2015, but significantly decreased by 18 % (10 %, 26 %) from 2016 to 2021. Hemorrhagic stroke rates stabilized in 2016-2021 (+3 %; -18 %, 30 %) after increasing in 2011-2015 (+36 %; 4 %, 78 %).

Conclusion: Improvements in ischemic and hemorrhagic stroke rates coincided temporally with increased uptake of OACs and a shift toward increased uptake of DOACs relative to warfarin.

Keywords: Atrial fibrillation; Hemorrhagic stroke; Ischemic stroke; Oral anticoagulation.