Definition
COVID-19
patients and disease severity
We included all patients with confirmed COVID-19 according toDiagnosis and Treatment Protocol for Novel Coronavirus Pneumonia
(trial seventh edition) by the Chinese National Health Commission11. Severity of
COVID-19 was categorized into three stages: Severe cases were defined as
(i) respiratory rate ≥ 30 breaths/min, (ii) oxygen saturation ≤ 93%, or
(iii) PaO2/FiO2 ratio ≤ 300 mmHg. Critical cases were defined as
including one or more of the following criteria: shock, respiratory
failure requiring mechanical ventilation, in combination with other
organ failures, or admission to ICU. Or else, other COVID patients were
general cases. In-hospital disease severity were the severest grade
during hospitalization.