1. The First School of Clinical Medicine, Southern Medical University, Baiyun District, Guangzhou, Guangdong, China
2. Department of Gastroenterology, Guangdong General Hospital and Guangdong Academy of Medical Sciences, South China University of Technology, Guangzhou, Guangdong, China
3. Guangdong Geriatrics Institute, Guangdong General Hospital and Guangdong Academy of Medical Sciences, South China University of Technology, Guangzhou, Guangdong, China