1. Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
2. Department of Hepatobiliary and Pancreas Surgery, University of California, Irvine Medical Center, Orange, California
3. Center for Health Management and Policy, Shandong University, Jinan, Shandong, China
4. Department of Gastrointestinal Surgery, Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China
5. Department of General Surgery, the Second Hospital of Shandong University, Jinan, Shandong, China