Yokohama City University - Department of Gastroenterology and Hepatology, Kitasato University - Department of Gastroenterology, Ogaki Municipal Hospital, Nayoro City General Hospital, Tokyo Medical University, Iwate Medical University, Hiroshima University, Hiroshima University - Department of Epidemiology, Infectious Disease Control and Prevention, St. Jude Children’s Research Hospital - Department of Epidemiology and Cancer Control, Musashino University, Musashino University, Musashino University, Yokohama City University - Department of Gastroenterology and Hepatology and Gifu Kyoritsu University