1. Division of Endoscopy Yokohama City University Medical Center Kanagawa Japan
2. Inflammatory Bowel Disease Center Yokohama City University Medical Center Kanagawa Japan
3. Departments of Biostatistics Yokohama City University Graduate School of Medicine Kanagawa Japan
4. Division of Diagnostic Pathology Yokohama City University Medical Center Kanagawa Japan
5. Department of Gastroenterology Yokohama City University Graduate School of Medicine Kanagawa Japan