Study to Learn More About the Benefits and Side-effects of Drugs Rivaroxaban and Apixaban Compared to the Drug Warfarin for Stroke Prevention in Patients With Rapid and Irregular Heartbeat Which is Not Due to a Heart-valve Fault (Non-valvular Atrial Fibrillation) in the UK Routine Clinical Practice

This population-based study will identify patients with rapid and irregular heartbeat which is not due to a fault with the heart valves (non-valvular atrial fibrillation) who initiate rivaroxaban, apixaban or warfarin as treatment for Stroke Prevention in Atrial Fibrillation (SPAF). Purpose of the study is to learn more about the safety and how well the drugs rivaroxaban, apixaban and warfarin work in patients appropriately and inappropriately receiving standard and reduced doses of each drug for reducing the risk of stroke in atrial fibrillation. Real world data from routine general practice stored in the primary care database in the UK, The Health Improvement Network (THIN), will be used for investigation.