1. Department of Gastroenterology, Suzhou Municipal Hospital, Suzhou, Anhui 234000, P.R. China
2. Medical Center for Digestive Diseases, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210011, P.R. China
3. Department of Gastroenterology, Central Hospital of Shandong Energy Zaozhuang Mining Group, Zaozhuang, Shandong 277100, P.R. China
4. Department of Gastroenterology, Qilu Hospital of Shandong University, Jinan, Shandong 250012, P.R. China