1. Department of Gastroenterology and Hepatology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto City 860-8556, Kumamoto, Japan
2. Sendai Kousei Hospital, 4-15 Sakamoto, Aoba-ku, Sendai City 980-0873, Miyagi, Japan
3. Department of Gastroenterology and Hepatology, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki City 852-8501, Nagasaki, Japan
4. Kumamoto Shinto General Hospital, 3-2-65 Ooe, Chuo-ku, Kumamoto City 862-8655, Kumamoto, Japan
5. Kumamoto Kenhoku Hospital, 550 Tamana, Tamana City 860-0005, Kumamoto, Japan
6. Public Health and Welfare Bureau, City of Kumamoto, 1-1 Tetori-honcho, Chuo-ku, Kumamoto City 860-8601, Kumamoto, Japan