Anticoagulants; Atrial Fibrillation/drug therapy; Embolism/prevention & control; Stroke/prevention & control; Aged; Aged, 80 and over; Anticoagulants/administration & dosage; Anticoagulants/adverse effects; Anticoagulants/classification; Atrial Fibrillation/complications; Benzimidazoles/administration & dosage; Benzimidazoles/adverse effects; Biological Availability; Comparative Effectiveness Research/methods; Comparative Effectiveness Research/statistics & numerical data; Dabigatran; Drug Monitoring/methods; Embolism/etiology; Embolism/mortality; Female; Humans; Male; Middle Aged; Morpholines/administration & dosage; Morpholines/adverse effects; Outcome and Process Assessment, Health Care; Pharmacovigilance; Pyrazoles/administration & dosage; Pyrazoles/adverse effects; Pyridones/administration & dosage; Pyridones/adverse effects; Randomized Controlled Trials as Topic; Risk Assessment/methods; Risk Assessment/statistics & numerical data; Rivaroxaban; Stroke/etiology; Stroke/mortality; Thiophenes/administration & dosage; Thiophenes/adverse effects; Warfarin/administration & dosage; Warfarin/adverse effects; beta-Alanine/administration & dosage; beta-Alanine/adverse effects; beta-Alanine/analogs & derivatives