1. Department of Internal Medicine, University of Medicine and Pharmacy, Ho Chi Minh, Vietnam
2. Department of Gastroenterology, Gia Dinh People’s Hospital, Ho Chi Minh City, Vietnam
3. Health Service Center, Hiroshima University, Higashihiroshima, Japan
4. Department of Endoscopy, Gia Dinh People’s Hospital, Ho Chi Minh City, Vietnam
5. Department of Endoscopy, Hiroshima University Hospital, Hiroshima, Japan
6. Department of Gastroenterology and Hepatology, National Center for Global Health and Medicine, Ichikawa, Japan