1. Department of Gastroenterology, Faculty of Medicine, University of Yamanashi, Chuo 409-3898, Japan
2. Department of Gastroenterology, Japan Community Health Care Organization Yamanashi Hospital, Kofu 400-0025, Japan
3. Yamanashi Koseiren Health Care Center, Yamanashi 400-0035, Japan
4. Department of Health Sciences, Faculty of Medicine, University of Yamanashi, Chuo 409-3898, Japan
5. Department of Gastroenterology, Otsuki Municipal Central Hospital, Otsuki 401-0015, Japan