1. Gastroenterology and Hepatology Unit, Division of Internal Medicine, Faculty of Medicine, Prince of Songkla University, Songkhla 90110, Thailand
2. Division of Pathology, Faculty of Medicine, Prince of Songkla University, Songkhla 90110, Thailand
3. Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, Songkhla 90110, Thailand
4. NKC Institute of Gastroenterology and Hepatology, Songklanagarind Hospital, Prince of Songkla University, Hat Yai, Songkla 90110, Thailand