Real-world effects of medications for stroke prevention in atrial fibrillation: protocol for a UK population-based non-interventional cohort study with validation against randomised trial results

Introduction Patients with atrial fibrillation experience an irregular heart rate and have increased risk of stroke; prophylactic treatment anticoagulation medication reduces this risk. Direct-acting oral anticoagulants (DOACs) been approved providing alternative to vitamin K antagonists such as warfarin. There is interest from regulatory bodies on the effectiveness medications in routine clinical practice; however, uncertainty remains regarding suitability non-interventional data for answering questions drug most suitable methods be used. In study, we will use Apixaban Reduction Stroke Other Thromboembolic Events Atrial Fibrillation (ARISTOTLE)—the pivotal trial DOAC apixaban—to validate assessing anticoagulants. These could then applied analyse people excluded or under-represented ARISTOTLE. Methods analysis Patient characteristics ARISTOTLE used select a cohort patients similar baseline two UK electronic health record (EHR) databases, Clinical Practice Research Datalink Gold Aurum (between 1 January 2013 31 July 2019). propensity score matching coarsened exact explored between EHR groups determine optimal method obtaining balanced cohort. Absolute relative outcomes trial-analogous calculated compared results; if results are deemed compatible can examine over longer duration exposure special patient not studied trial. Ethics dissemination The study has by Independent Scientific Advisory Committee Medicines Healthcare Products Regulatory Agency. Results disseminated scientific publications at relevant conferences.