Potential confounders
Potential confounders were identified literature review. Directed acyclic graphs (DAG) were subsequently drawn to visualize causal assumptions to identify confounders (Figure S1 in the online supplement). Age, sex, body mass index (BMI), medical history of chronic pulmonary disease, diabetes mellitus, active malignancy, hypertension, obstructive coronary heart disease, myocardial infarction, nonischaemic cardiomyopathy, heart failure, previous heart surgery, electronic heart device, cerebrovascular accidents, and/or peripheral artery disease, use of immunosuppressive medication, and no-ICU policy were identified as confounders that were available in our database.