1. Department of Gastroenterology, Affiliated Hospital of Southwest Medical University, Luzhou, China;
2. Department of Gastroenterology, the People’s Hospital of Lianshui, Huaian, China;
3. Departmemt of Gastroenterology, Beijing Tsinghua Changgung Hospital Medical Center, Tsinghua University, Beijing, China;
4. Department of Gastroenterology, the Affiliated Hospital of North Sichuan Medical College, Nanchong, China