1. Department of Gastroenterology, Longgang District People's Hospital of Shenzhen, Shenzhen, Guangdong 518116, P.R. China
2. Department of Gastroenterology, Zhuhai Hospital of Traditional Chinese and Western Medicine, Zhuhai, Guangdong 519000, P.R. China
3. Department of Gastroenterology, Guangdong Provincial Key Laboratory of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China