1. Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Toon, Ehime 791-0295, Japan
2. Department of Community Medicine, Ehime University Graduate School of Medicine, Toon, Ehime 791-0295, Japan
3. Center for Liver-Biliary-Pancreatic Diseases, Matsuyama Red Cross Hospital, Matsuyama, Ehime 790-0826, Japan
4. Internal Medicine, Saiseikai Imabari Hospital, Imabari, Ehime 799-1502, Japan