1. Department of Respiratory Medicine, Huashan Hospital, Fudan University; Shanghai China
2. Department of Respiratory Medicine, Shaanxi Normal University Hospital; Shaanxi China
3. Department of Anesthesiology, Grade 2014, Chongqing Medical University; Chongqing China
4. Department of Medical Statistics, Fourth Military Medical University; Xi'an China
5. Department of Pulmonary and Critical Care Medicine, Xijing Hospital, Fourth Military Medical University; Xi'an China
6. Department of Respiratory Medicine, The Fourth People's Hospital of Shaanxi Province; Xi'an China
7. Department of Respiratory Medicine, Xi'an Aerospace General Hospital; Xi'an China