1. Department of General Surgery, Northern Jiangsu People's Hospital, Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China
2. Department of General Surgery, Yizhen People's Hospital, Yangzhou University, Yangzhou, Jiangsu 225001, P.R. China
3. Division for Health Service Promotion, University of Tokyo Hospital, Tokyo 113‑0033, Japan