1. Department of Hepatobiliary Surgery , Affiliated Hospital of North Sichuan Medical College , Nanchong , China
2. Institute of Hepato-Biliary-Pancreatic-Intestinal Disease, North Sichuan Medical College , Nanchong , China
3. Nanchong Psychosomatic Hospital , Nanchong , China
4. Department of Clinical Statistics , Affiliated Hospital of North Sichuan Medical College , Nanchong , China