1. Otorhinolaryngology Department, Cho Ray hospital, Ho Chi Minh City, Vietnam
2. Department of Medical Statistics and Informatics, Faculty of Public Health, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam
3. Head and Neck Surgery Department, ENT Hospital, Ho Chi Minh City, Vietnam
4. Digestive Surgery Department, Cho Ray hospital, Ho Chi Minh City, Vietnam
5. Department of General Surgery, Faculty of Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam