1. Department of Traumatology and Acute Critical Medicine; Osaka University Graduate School of Medicine; Osaka Japan
2. Department of Gastroenterology and Hematology; Hirosaki University Graduate School of Medicine; Aomori Japan
3. Division of Gastroenterology and Hepatology; Department of Internal Medicine; Tokai University School of Medicine; Kanagawa Japan
4. Office of Biostatistics and Data Management; National Cerebral and Cardiovascular Center; Osaka Japan