1. Department of General Surgery, Gansu Provincial Hospital, Lanzhou, Gansu, China
2. Ningxia Medical University, Yinchuan, Ningxia, China
3. Institution of Clinical Research and Evidence-Based Medicine, the Gansu Provincial Hospital, Lanzhou, Gansu, China
4. Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Lanzhou, Gansu, China
5. Department of Clinical Medicine, The First Clinical Medical College of Lanzhou University, Lanzhou, Gansu, China
6. Key Laboratory of Evidence-Based Medicine Knowledge Translation of Gansu Province, Lanzhou, Gansu, China