1. Department of Gastroenterology, Okinawa Chubu Hospital, 271 Miyazato, Uruma 904-2293, Japan
2. School of Psychology and Healthcare Management at Akasaka, Department of Healthcare Management, International University of Health and Welfare, 4-1-26 Akasaka, Minato, Tokyo 107-8402, Japan
3. Division of Gastroenterology, Yaeyama Hospital, 584-1 Maezato, Ishigaki 907-0002, Okinawa, Japan