1. Gastroenterology Division; Saiseikai Yokohama-shi Nanbu Hospital; Yokohama Japan
2. Gastroenterology Division; Yokohama City University School of Medicine; Yokohama Japan
3. Department of Biostatistics and Epidemiology; Yokohama City University School of Medicine; Yokohama Japan
4. Department of Gastroenterology; Machida Municipal Hospital; Machida Tokyo Japan
5. Department of Gastroenterology; International University of Health and Welfare Atami Hospital; Atami Shizuoka Japan
6. Department of Gastroenterology; Tokyo Metropolitan; Hiroo General Hospital; Shibuya-ku Tokyo Japan
7. Department of Gastroenterology; Yokosuka City Hospital; Yokosuka Kanagawa Japan
8. Department of Gastroenterology; Yokohama Minami Kyosai Hospital; Yokosuka Kanagawa Japan
9. Department of Gastroenterology; NTT Medical Center Tokyo; Gotanda Tokyo Japan
10. Department of Gastroenterology and Hepatology; Yokohama City University School of Medicine; Yokohama Japan