1. Evidence-based Medicine Center, Medical School of Nantong University, Jiangsu, China
2. Department of Gastroenterology, Lianyungang No 1 People’s Hospital, Jiangsu, China
3. Department of Infectious Disease, Ningxiang People’s Hospital, Hunan, China
4. Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, USA