Characteristics of cohort included in the study
The total Medicare population was 364348 persons with 347976 individuals contributing data to the medical databases. The final cohort included in this study consisted of 280592 persons (mean age (SD) 72.5 (9.9) years; 58.8% female) (table 1) after applying the following exclusions: (i) AF patients in the 2-year baseline period as defined by IC10 codes and anticoagulant/rhythm control medications; and (ii) AF conditions prior to the occurrence of incident COVID-19 conditions upon entry into the study and occurring in the same reporting day for COVID-19 conditions. There was a diversified multi-morbid history with (a) hypertension and lipid disorders having the highest prevalence, >65%, followed by (b) spondylosis/ intervertebral disc and osteoarthritis, with prevalence >30%, then prevalence in the range of 15-20% for diabetes, coronary artery disease, anemia, and COPD. Other conditions had lower prevalence rates as shown in table 1.