1. Department of Digestive Diseases; Xijing Hospital of Fourth Military Medical University; Xi'an; Shannxi; China
2. Department of Digestive Diseases; China PLA General Hospital; Beijing; China
3. Department of Digestive Diseases; Friendship Hospital of Capital Medical University; Beijing; China
4. Department of Digestive Diseases; Ruijin Hospital of Shanghai Jiaotong University; Shanghai; China
5. Department of Digestive Diseases; Changhai Hospital of Second Military Medical University; Shanghai; China
6. Department of Digestive Diseases; Affiliated No. 1 Hospital of Zhongshan University; Guangzhou; China
7. Department of Digestive Diseases; Nanfang Hospital of Southern Medical University; Guangzhou; China
8. Department of Digestive Diseases; Tangdu Hospital of Fourth Military Medical University; Xi'an; Shannxi; China