The Tasmanian Atrial Fibrillation Study: Transition to direct oral anticoagulants 2011-2015

Introduction: Contemporary Australian data regarding antithrombotic prescribing patterns following approval of direct oral anticoagulants (DOACs) in patients with atrial fibrillation (AF) are limited.

Aim: The aim of the present study was to assess antithrombotic prescribing patterns before, during and after the clinical introduction of DOACs.

Methods: Using digital medical records, this retrospective cohort study included all patients with AF as a primary or secondary diagnosis who were admitted to the Royal Hobart Hospital, Tasmania, Australia, between January 2011 and July 2015.

Results: Antithrombotic agents were prescribed for 2078 (91.9%) of 2261 patients without documented contraindication to therapy. Higher rates of OAC prescribing were observed following Government subsidization of DOACs in Quarter 3 (Q3) 2013 than anticoagulation rates in the prior quarters, (54.4% in Q3, 2013 to 68.1% in Q2, 2015, p < 0.001), with the prescribing of warfarin and antiplatelet agents declining. DOACs, as a class, accounted for 18.4% of patients on antithrombotic therapy in 2011 -2015; the proportion of patients receiving a DOAC steadily increased from 3.9% among OAC users in Q3, 2011 to 67.6% in Q2, 2015 (p < 0.001). In a sub-set of patients with newly diagnosed AF, patients commenced on DOACs were younger (70.4 vs. 73.8 years, p = 0.04) and had lower stroke and bleeding risk scores (CHA2DS2-VASc 2.8 vs. 3.3, p = 0.03, HAS -BLED 2 vs. 3, p  = 0.04) than patients who were newly prescribed warfarin.

Conclusions: DOACs rapidly became the most commonly prescribed class of antithrombotic medications in patients with AF soon after they became widely available. Warfarin and antiplatelet prescribing declined significantly, although a substantial proportion of patients continued to be prescribed antiplatelet therapy. Patients who were initiated on DOACs were typically younger with fewer comorbid conditions compared to those initiated on warfarin therapy.