1. Department of General Surgery, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, P.R. China
2. Department of Biostatistics, School of Public Health, Medical College of Soochow University, Suzhou, Jiangsu 215123, P.R. China
3. Department of Gastroenterology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, P.R. China