Effectiveness and safety of non-vitamin K antagonist oral anticoagulants in patients with atrial fibrillation at low risk of stroke in japan: a retrospective cohort study.

Aims: Contemporary guidelines differ in their recommendations regarding initiating non-vitamin K antagonist oral anticoagulants (NOACs) in patients with atrial fibrillation (AF) at low risk of stroke. This study aimed to examine the effectiveness and safety of NOACs for low-risk AF in a Japanese cohort.

Methods and results: In this retrospective cohort study based on the JMDC Claims Database extracted between April 2011 and November 2022, we identified 13 291 patients with AF at low risk of stroke. We performed inverse probability of treatment weighting Cox regression analyses to compare the embolization and bleeding risks between the nontreatment and NOAC groups. Net clinical benefit was defined as the annual incidence of ischaemic stroke events prevented by NOACs after subtracting intracranial haemorrhage (ICH) events attributable to NOACs, multiplied by a weighting factor. The incidences of stroke and ICH in the nontreatment group were 0.47 and 0.15 per 100 person-years, respectively. The NOAC group had higher incidences of ICH (hazard ratio [HR]: 1.73, 95% confidence interval [CI]: 0.75-4.00) and stroke (HR: 1.41, 95% CI: 0.84-2.36). The net clinical benefit of NOAC treatment was -0.35% per year (95% CI: -0.99-0.29%).

Conclusion: Non-vitamin K antagonist oral anticoagulants treatment may be associated with a slightly high risk of ICH, and it yielded a neutral clinical benefit in the present Japanese population, which provides reassurance concerning the role of ethnicity in NOAC treatment for patients with AF and suggests a need to assess comprehensive weighting of the respective risk factors.