1. Department of Clinical Epidemiology and Health Economics, School of Public Health, University of Tokyo, Tokyo, Japan
2. Department of Gastroenterology, Saiseikai Kawaguchi General Hospital, Saitama, Japan
3. Department of Health Policy and Informatics, Tokyo Medical and Dental University, Graduate School of Medicine, Tokyo, Japan
4. Department of Gastroenterology, Toranomon Hospital, Tokyo, Japan