1. Department of Gastroenterology and Hepatology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China;
2. Department of Gerontology, Tibetan Chengdu Branch Hospital of West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
3. Department of Gastroenterology and Hepatology, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China