1. Department of Surgery Pattani Hospital Pattani Thailand
2. Center for Clinical Epidemiology & Clinical Statistics, Faculty of Medicine Chiang Mai University Chiang Mai Thailand
3. Surgical Endoscopy Unit, Department of Surgery Rajavithi Hospital Bangkok Thailand
4. Department of Medical Services Ministry of Public Health Bangkok Thailand
5. Clinical Surgical Research Center Chiang Mai University Chiang Mai Thailand
6. Department of Surgery, Faculty of Medicine Chiang Mai University Chiang Mai Thailand