1. Department of Surgery, Nakornping Hospital, Chiang Mai 50180, Thailand
2. Division of Gastrointestinal Surgery and Endnoscopy, Department of Surgery, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
3. Department of Obstetrics & Gynecology, Nakornping Hospital, Chiang Mai 50180, Thailand
4. Department of Emergency Medicine, Nakornping Hospital, Chiang Mai 50180, Thailand
5. Clinical Epidemiology Unit & Clinical Research Center, Faculty of Medicine, Thammasat University, Pathum Thani 12120, Thailand