Disparities in oral anticoagulation initiation in patients with schizophrenia and atrial fibrillation: A nationwide cohort study.

AIMS: Schizophrenia is associated with poor anticoagulation control and clinical prognosis in patients with atrial fibrillation (AF). Little is known about initiation of oral anticoagulation therapy (OAC) in this patient population. METHODS: In the nationwide Danish health registries, we identified all patients with incident AF and schizophrenia with indication for OAC treatment. Patients with schizophrenia (n = 673) were matched 1:5 on sex, age, stroke risk score, and calendar-period to incident AF patients without schizophrenia. We calculated absolute risk and risk difference (RD) of OAC initiation, adjusting for stroke and bleeding risk factors. Analyses were stratified by calendar period (2000-2011 and 2012-2018) to account for changes after the introduction of non-vitamin K OACs (NOAC). RESULTS: Among patients with schizophrenia (mean age 69.5 years, 50.3% females), 33.7% initiated OAC within the first year after AF diagnosis, compared with 54.4% of patients without schizophrenia, corresponding to an adjusted RD of -20.7 (95% confidence interval [CI]: -24.7 to -16.7). OAC initiation increased over time regardless of schizophrenia status. During 2000-2011, 18.3% of patients with schizophrenia and 42.9% without schizophrenia initiated OAC (adjusted RD -23.6%, 95% CI -28.8 to -18.6). During 2012-2018, this was 48.5% and 65.7%, respectively (adjusted RD -14.4%, 95% CI -20.4 to -8.4). CONCLUSION: Initiation of OAC was substantially lower among patients with AF and schizophrenia compared with matched AF peers. These findings accentuate the importance of close attention to disparities in initiation of OAC treatment, and potential missed opportunities for prevention of disabling strokes in AF patients with schizophrenia.