1. Department of General Surgery, Beijing Friendship Hospital, Capital Medical University & National Clinical Research Center for Digestive Diseases, Beijing 100050, China
2. School of Public Health, Peking University, Beijing 100191, China
3. Department of General Surgery, Nanjing Drum Tower Hospital, Nanjing, Jiangsu 210008, China
4. Department of Metabolic and Bariatric Surgery, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510630, China
5. Center of Gastrointestinal and Minimally Invasive Surgery, Department of General Surgery, The Third People's Hospital of Chengdu & The Affiliated Hospital of Southwest Jiaotong University, Chengdu, Sichuan 610014, China
6. Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, China
7. Center for Obesity and Metabolic Surgery, Huashan Hospital, Fudan University, Shanghai 200030, China
8. Department of Metabolic and Bariatric Surgery, Xiaolan People's Hospital of Zhongshan, Zhongshan, Guangdong 528415, China
9. Department of General Surgery, First Affiliated Hospital with Nanjing Medical University, Nanjing, Jiangsu 226399, China
10. Department of General Surgery, Zhongshan Hospital, Shanghai 200032, China
11. Department of Gastrointestinal Surgery, Dongfang Hospital of Shaghai, Shanghai 200120, China
12. Department of General Surgery, Beijng Hospital, Beijing 100730, China
13. Department of Gastrointestinal Surgery, Zibo Central Hospital, Zibo, Shandong 255020, China
14. Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China
15. Department of Bariatric and Metabolic Surgery, Shanghai Jiao Tong University affiliated Sixth People's Hospital, Shanghai 200233, China
16. Department of Gastrointestinal Surgery,The Third Xiangya Hospital of Central South University, Changsha, Hunan 410013, China.