1. Department of Internal Medicine University of Medicine and Pharmacy at Ho Chi Minh City Ho Chi Minh City Vietnam
2. Department of Gastroenterology Nhan Dan Gia Dinh Hospital Ho Chi Minh City Vietnam
3. Department of Internal Medicine, School of Medicine Tan Tao University Long An Vietnam
4. Department of Endoscopy University Medical Center Ho Chi Minh City Vietnam
5. Department of Endoscopy Nhan Dan Gia Dinh Hospital Ho Chi Minh City Vietnam
6. Health Service Center, Hiroshima University Higashihiroshima Japan