Effectiveness and Safety of Direct Oral Anticoagulants versus Aspirin in Patients with Non-Valvular Atrial Fibrillation and Intermediate Stroke Risk

Aims This study compared the effectiveness and safety of direct oral anticoagulants (DOACs) versus aspirin for stroke prevention in patients with non-valvular atrial fibrillation (NVAF) and intermediate stroke risk, defined by a CHA 2 DS 2 -VASc score of 1 in men and 2 in women. Method This retrospective cohort study used Korean Health Insurance Review and Assessment Service claims data. Patients diagnosed with NVAF between January 1, 2017, and December 31, 2019, who initiated DOACs or aspirin, were included. Eligibility was restricted by CHA 2 DS 2 -VASc score, and patients were matched by age and sex to reduce confounding. The observation period extended until November 30, 2021. The primary outcomes were the incidence of ischemic stroke (effectiveness) and major bleeding events (safety). Results Of the 2234 patients included, 977 (43.7%) were treated with DOACs, and 1257 (56.3%) received aspirin. After matching, no statistically significant differences were observed between the DOAC and aspirin groups in ischemic stroke incidence (1.46 vs 0.92 per 100 person-years, P = .060) or major bleeding events (2.26 vs 2.10 per 100 person-years, P = .100). Notably, rheumatic disease was associated with an increased risk of ischemic stroke, while liver disease was linked to a higher risk of major bleeding. Conclusion In NVAF patients with intermediate stroke risk, no statistically significant differences were observed in ischemic stroke or major bleeding between DOACs and aspirin. These results should not be interpreted as therapeutic equivalence but highlight the need for further real-world research, particularly in Asian populations, to inform optimal antithrombotic strategies in this subgroup.