Safety and clinical effectiveness of direct oral anticoagulants in patients with atrial fibrillation in Scotland

Background: Direct oral anticoagulants (DOACs), used long - term in patients with atrial fibrillation (AF), have proven safe and efficacious in clinical trials. However, information regarding their safety and clinical effectiveness in the real world is still limited. Methods: Retrospective cohort study using linked routinely collected administrative data. Patients had a diagnosis of AF and received a first prescription for a DOAC between September 2011 and December 2015. Treatment outcomes, stratified by drug, will be analysed using time dependent Cox proportional hazard models; drug exposure will be defined as days’ supply. Clinical endpoints will include stroke, systemic embolism, and death due to cardiovascular reasons; the main safety indicator will be major bleeds. Preliminary results: A total of 14,721 patients initiated DOAC treatment during the study period; 6,231 with apixaban, 1,123 with dabigatran, and 7,367 with rivaroxaban. The majority of DOAC treatments were initiated in 2014 (32.2%) and 2015 (47.3%). Median time of follow - up was 346 [IQR 167 – 597] days, ranging from 260 [IQR 122.5 – 435] days for apixaban to 864 [IQR 536.5 – 1170] days for dabigatran. Mean age at time of first prescription was 74.1 [SD11.3] years (range 71.1 [SD 12.0] – 74.8 [SD 11.0] years), and 45.5% were female (range 37.3 – 46.5%). Polypharmacy was observed in 87.6% of all patients (range 82.9 – 88.6%), and mean CHA₂DS₂ - VASc score was 2.9 [SD 1.7] (range 2.5 [SD1.7] – 3.0 [SD 1.7]). During the study period, 385 patients had a stroke (apixaban 120, dabigatran 48, rivaroxaban 217); gastrointestinal bleeds occurred in 314 patients (88, 36, and 190, respectively), and 976 patients died due to cardiovascular reasons (282, 97, and 597, respectively). Conclusion: To prevent strokes, AF patients in Scotland increasingly receive DOACs instead of warfarin. Findings from this study will inform patient care and enable improvement of treatment outcomes.