1. School of Public Health, Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
2. Department of Gastrointestinal Surgery, The Third Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530031, P.R. China
3. Department of Hepatobiliary Surgery, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China