Bleeding-related admissions in patients with atrial fibrillation receiving antithrombotic therapy: results from the Tasmanian Atrial Fibrillation

Purpose: Limited data are available from the Australian settingregarding bleeding in patients with atrial fibrillation (AF)receiving antithrombotic therapy. We aimed to investigate theincidence of hospital admissions due to bleeding and factorsassociated with bleeding in patients with AF who receivedantithrombotic therapy.Methods: A retrospective cohort study was conducted involvingall patients with AF admitted to the Royal HobartHospital, Tasmania, Australia, between January 2011 andJuly 2015. Bleeding rates were calculated per 100 patientyears(PY) of follow-up, and multivariable modelling wasused to identify predictors of bleeding.Results: Of 2202 patients receiving antithrombotic therapy,113 presented to the hospital with a major or minor bleedingevent. These patients were older, had higher stroke and bleedingrisk scores and were more often treated with warfarin andmultiple antithrombotic therapies than patients who did notexperience bleeding. The combined incidence of major andminor bleeding was significantly higher in warfarin- versusdirect-acting oral anticoagulants (DOAC)- and antiplatelettreatedpatients (4.1 vs 3.0 vs 1.2 per 100 PY, respectively;p = 0.002). Similarly, the rate of major bleeding was higher inpatients who received warfarin than in the DOAC and antiplateletcohorts (2.4 vs 0.4 vs 0.6 per 100 PY, respectively;p = 0.001). In multivariate analysis, increasing age, priorbleeding, warfarin and multiple antithrombotic therapies wereindependently associated with bleeding.Conclusion: The overall rate of bleeding in this cohort waslow relative to similar observational studies. The rate of majorbleeding was higher in patients prescribed warfarin comparedto DOACs, with a similar rate of major bleeding for DOACsand antiplatelet agents. Our findings suggest potential to strategiesto reduce bleeding include using DOACs in preferenceto warfarin, and avoiding multiple antithrombotic therapies inpatients with AF