Data collection
Demographics, laboratory values, treatment strategies, complications, and clinical outcomes of patients were abstracted from the medical records using a standardized report form designed for this study. The clinical symptoms and laboratory findings at hospital admission and complications and clinical outcomes throughout the hospitalization were collected. Acute respiratory distress syndrome (ARDS) was defined according to the Berlin definition9. The severe condition of COVID-19 was determined using the guideline for the diagnosis and treatment of 2019 novel coronavirus (2019-nCoV) infected pneumonia (standard version)10. Acute kidney injury was defined based on the KDIGO (Kidney Disease: Improving Global Outcomes) criteria11. Acute liver injury was defined according to the EASL Clinical Practice Guidelines12. The primary outcome of this study was survival. The secondary outcomes included the severity of illness, ARDS, acute liver injury, and acute kidney injury. Patients’ follow-up times were defined as the time interval from hospitalization to the most recent contact or the time of patient death, whichever came earlier. The latest follow-up date was March 15, 2020.