Study design and resulting study population. (A) Diagram of the study design. All time periods that were considered to determine patient conditions prior to OAC initiation included the date of OAC initiation itself. (B) Patient characteristics according to OAC treatment. Data are expressed as column %, unless otherwise specified. An absolute standardized difference <0.1 was considered to indicate a negligible between-group difference. Additional characteristics are given in supplemental Table 1: age at index date, year, in classes (18 to 49, 50 to 59, 60 to 64, 65 to 69, 70 to 74, 75 to 79, 80 to 84), deprivation index of the area of residence, arrhythmias (other than AF), history of ATE, dementia or Parkinson disease, epilepsy or mental illness, history of DVT/PE, opioid-related disorders, HIV infection, other chronic and debilitating diseases, thyroid disease, oral corticosteroids, opioids and other analgesics, antiulcer agents, hypnotics or anxiolytics, polymedication at index date (<5, 5 to 9, ≥10 ATC classes), number of general practitioner visits during the year before OAC initiation (0, 1 to 5, 6 to 11, ≥12), influenza vaccination during the vaccination campaign directly preceding OAC initiation, first OAC prescriber’s specialty (hospital practitioner, general practitioner, private cardiologist, other private practitioners), calendar year of OAC initiation. ATC, anatomical therapeutic chemical; ATE, arterial thromboembolic events (ischemic stroke, arterial systemic embolism or transient ischemic attack); COPD, chronic obstructive pulmonary disease; DVT/PE, deep vein thrombosis/pulmonary embolism; NSAIDs, nonsteroidal anti-inflammatory drugs; SD, standard deviation; STD. standardized difference.