Background Co-prescribing a proton pump inhibitor (PPI) with an anticoagulant, in patients with atrial fibrillation (AF) at high risk of bleeding, decreases the risk of gastrointestinal bleeding. This study aimed to identify Australian prescribing trends for this topic to inform practice in this area. Methods This was a retrospective cohort study in which a cross-sectional analysis of general practice data obtained from MedicineInsight was performed, to evaluate current Australian prescribing trends of PPIs in patients with AF. Patients aged 18 years or more initiated on an oral anticoagulant between January 1st, 2011 and April 25th, 2019 were included. Results A total of 28,863 participants were included; of these, 5,092 (17.6%) received PPI co-therapy. There were 4,211 (14.6%) participants at high risk of bleeding, with 878 (20.9%) of these receiving PPI co-therapy. Participants were significantly more likely to be prescribed a PPI if prescribed dabigatran (adjusted odds ratio (AOR) 1.42 [1.28-1.57], 95% confidence interval (CI)), apixaban (AOR 1.36 [1.26-1.46], 95%CI) or rivaroxaban (AOR 1.28 [1.18-1.38], 95%CI) compared to warfarin. Factors associated with PPI prescribing included, antiplatelet co-therapy (AOR 2.09 [1.82-2.39], 95% CI), high CHA2DS2-VASc score (≥2 male or ≥3 female) (AOR 1.50 [1.28-1.77], 95% CI) and a low ORBIT score (<3) (AOR 1.42 [1.23-1.64], 95% CI). Conclusion In this large nationally representative cohort, only 20.9% of participants who were at high risk of bleeding were co-prescribed a PPI. Further research is required to investigate whether increased prescribing of PPIs could improve patient outcomes. Key words: Atrial fibrillation, proton pump inhibitors

Approval of direct-acting oral anticoagulants (DOACs) for stroke prevention in atrial fibrillation (AF) was an important milestone, providing widened treatment choices along with the possibility for inter-drug switching after initiation. In addition to improved utilisation of oral anticoagulants (OACs) for stroke prevention, reports of switching among OACs are growing in the literature. Switching may influence clinical outcomes, healthcare costs and patient satisfaction. This review aimed to summarise the current literature on the pattern of OAC switching in patients with AF, including reasons for switching and clinical consequences following switching. We included articles published after 2013, following the introduction of apixaban; searched on June 27, 2020 from PubMed, Scopus and Embase. The review found that switching among OACs was common in clinical practice, significantly varying with the type of OAC. Studies reporting the reason for switching and clinical outcomes were comparatively limited. The reasons were often related to safety issues, poor anticoagulation control and ease of use. Factors that can increase the risk of bleeding and stroke were found to be associated with switching from vitamin K antagonists, but less for DOAC switching. Findings regarding bleeding outcomes following switching were inconsistent, possibly confounded with the type of OAC, reasons for switching and switching protocol. Despite the limited number of studies included and their relatively short follow-up periods, our review revealed that switching had minimal impact on stroke and other related thrombotic outcomes. Further prospective studies are needed to better understand possible reasons for switching and its influence on clinical outcomes.