1 Department of Gastroenterology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China.
2 Medical Research Center, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing 100730, China.
3 State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Beijing 100730, China.
4 Department of Epidemiology and Biostatistics, School of Population Medicine and Public Health, Peking Union Medical College, Chinese Academy and Medical Sciences, Beijing 100730, China.
5 Department of Family Medicine and Primary Care, JC School of Public Health and Primary Care, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong 999077, China.
6 Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton,Ontario L8S4L8, Canada.
7 Centre for Health Economics and Policy Analysis, McMaster University, Hamilton, Ontario L8S4L8, Canada.
8 Clinical Epidemiology Unit, International Clinical Epidemiology Network, Beijing 100730, China.