The Tasmanian atrial fibrillation study: Transition to direct oral anticoagulants 2011-2015

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

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

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.

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<.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<.001). In a subset of patients with newly diagnosed AF, patients commenced on DOACs were younger (70.4 vs 73.8 years, P=.04) and had lower stroke and bleeding risk scores (CHA2DS2-VASc 2.8 vs 3.3, P=.03, HAS-BLED 2 vs 3, P=.04) than patients who were newly prescribed warfarin.

Direct oral anticoagulants 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 with those initiated on warfarin therapy.