Early, low-dose, short-term methylprednisolone decreased the mortality in critical COVID-19 patients: A multicenter retrospective cohort studyJi, Jingjing; Wu, Ming; Zhong, Li; Liu, Zheying; Wang, Conglin; Shao, Ziyun; Xie, Qifeng; Liu, Zhifeng*Science Citation Index Expanded贵州大学; 南方医科大学; 深圳市第二人民医院; 1摘要-关键词-