1. Department of Endoscopy Shanghai Jiao Tong University Affiliated Sixth People's Hospital Shanghai China
2. Division of Gastroenterology and Hepatology Renji Hospital, Shanghai Institute of Digestive Disease, School of Medicine, Shanghai Jiao Tong University Shanghai China
3. Department of Gastroenterology Affiliated People's Hospital of Ningbo University Ningbo Zhejiang Province China
4. Changning District Centre for Disease Control and Prevention Shanghai China