Study participants
This study was a retrospective observational study. All patients with COVID-19 consecutively admitted to six wards in the Sino-French New City Branch of Tongji Hospital, Huazhong University of Science and Technology, from January 28 to March 9, 2020, were enrolled. Tongji Hospital was designated to treat severe and critical COVID-19 patients by the Wuhan government in January 2020. Follow-up of the clinical outcomes of all patients was censored on March 27, 2020.