To adjust for the confounding variables of this observational study, the researchers noted the following for each patient:

• Age

• Sex

• Patient-reported race and ethnic group

• Current insurance carrier

• First recorded vital signs on presentation

• Ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen (Pao2:Fio2) at admission

• First recorded BMI (the patient’s weight in kg divided by the square of the height in meters), according to CDC guidelines for adults

• First recorded inpatient laboratory tests

• Past and current diagnoses (diabetes, underlying kidney disease, chronic lung disease, hypertension)

• Patient-reported smoking status

• Medication administration at baseline