Qingdao University, Qingdao University, Shandong Medical University, Shandong University, Shandong University, Shandong First Medical University, Qingdao University - Yantai Yuhuangding Hospital, Weifang People's Hospital, Dongying People's Hospital, Qingdao University - Weihai Central Hospital, Qingdao University - Qingdao Municipal Hospital, Weihai Municipal Hospital, Jining People's Hospital, Rizhao People's Hospital, Rizhao People's Hospital, Qingdao University, Shandong First Medical University, Qingdao University, Qingdao University, Qingdao University, College of Medical Science, First Affiliated Hospital, Department of General Surgery, University of Copenhagen and Qingdao University