1. Department of Gastroenterology, Guangzhou Digestive Disease Center, Guangzhou Key Laboratory of Digestive Disease, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, Guangdong 510180, P.R. China
2. Department of Gastroenterology, The 2nd Clinical Medicine College (Shenzhen People's Hospital) of Jinan University, Shenzhen People's Hospital, Shenzhen, Guangdong 518020, P.R. China