1. 1Department of Digestive internal medicine, Heping Hospital Affiliated to Changzhi Medical College, Shanxi, Changzhi 046000, China
2. 2Department of Epidemiology, School of Public Health, Southern Medical University, Guang-dong, Guangzhou 510515, China
3. 3Institute of Evidence-Based Medicine, Heping Hospital Affiliated to Changzhi Medical College, Shanxi, Changzhi 046000, China