1 The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China.
2 Department of Gastroenterology, Guangdong Provincial Geriatrics Institute, National Key Clinical Specialty, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China.
3 Department of Gastroenterology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, South China University of Technology, Guangzhou, China.