Data collection

The medical record of each COVID-19 patient was evaluated on admission. The following data were collected from the electronic medical records: demographic information, preexisting comorbidities, including chronic obstructive pulmonary disease, hepatic disease, cardiovascular disease, hypertension, diabetes mellitus and other disease. Patient’s signs and symptoms, and laboratory test results were also collected. The dates of onset, admission and death were recorded. The onset time was defined as the date when any symptom and sign were found.