Study design
This study was a single-center retrospective study with an application from the Biomedical Ethics Committee of West China Hospital of Sichuan University,Located in Sichuan Province in western China, being a large tertiary teaching hospital with 4,300 beds and a designated hospital for non-COVID-19 patients.Patients,diagnosed with pneumonia upon admission to West China Hospital from January 1,2019 to Dec 31,2021 were included.The study protocol was approved by the Ethics Committee of the West China Hospital and the participating hospitals.We took December 8,2019 as the cut-off point,defined as pre-COVID-19, and post-COVID-19, as the first COVID-19 patient officially confirmed in Wuhan occurred on this day.We collect the patient’s dates, including: gender, age, admission, department distribution, hospital days, underlying diseases (including hypertension, diabetes, coronary heart disease,heart-failure,chronic obstructive pulmonary disease(COPD), renal failure ,Immunosuppression),viral nucleic acid test after admission, Invasive ventilation support,etc.