1. Department of Gastroenterology, Geriatric Hospital of Nanjing Medical University, Nanjing, Jiangsu 210024, P.R. China
2. Department of Gastroenterology, Geriatric Hospital of Nanjing Medical University, Nanjing, Jiangsu 210024
3. Department of Gastroenterology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China