1. Department of Gastroenterology & Hepatology, West China Hospital, Sichuan University, Chengdu, China;
2. Sichuan University-Oxford University Huaxi Gastrointestinal Cancer Centre, West China Hospital, Sichuan University, Chengdu, China;
3. Department of Gastroenterology, The First People's Hospital of Longquanyi District Chengdu, Chengdu, Sichuan, China;
4. Department of Gerontology, Hospital of Chengdu Office of People's Government of Tibetan Autonomous Region, Chengdu, China;