Oral Anticoagulant Treatment and the Risk of Dementia in Patients With Atrial Fibrillation: A Population‐Based Cohort Study

BACKGROUND: We compared the dementia incidence rate between users and nonusers of oral anticoagulants (OACs) in a large cohort of primary care patients with atrial fibrillation. METHODS AND RESULTS: We performed a retrospective study using an Australia‐wide primary care data set, MedicineInsight. Patients aged ≥18 years and newly diagnosed with atrial fibrillation between January 1, 2010, and December 31, 2017, and with no recorded history of dementia or stroke were included and followed until December 31, 2018. We applied a propensity score for 1:1 pair matching of baseline covariates and Cox regression for comparing the dementia incidence rates for OAC users and nonusers. Data were analyzed for 18 813 patients with atrial fibrillation (aged 71.9±12.6 years, 47.1% women); 11 419 had a recorded OAC prescription for at least 80% of their follow‐up time. During the mean follow‐up time of 3.7±2.0 years, 425 patients (2.3%; 95% CI, 2.1%–2.5%) had a documented diagnosis of dementia. After propensity matching, the incidence of dementia was significantly lower in OAC users (hazard ratio [HR], 0.59; 95% CI, 0.44–0.80; P<0.001) compared with nonusers. Direct‐acting oral anticoagulant users had a lower incidence of dementia than non‐OAC users (HR, 0.49; 95% CI, 0.33–0.73; P<0.001) or warfarin users (HR, 0.46; 95% CI, 0.28–0.74; P=0.002). No significant difference was seen between warfarin users and non‐OAC users (HR, 1.08; 95% CI, 0.70–1.70; P=0.723). CONCLUSIONS: In patients with atrial fibrillation, direct‐acting oral anticoagulant use may result in a lower incidence of dementia compared with treatment with either warfarin or no anticoagulant.