1. Lanzhou University; Evidence-Based Medicine Center, School of Basic Medical Sciences; No. 199, Donggang West Road Lanzhou City Gansu China 730000
2. Lanzhou University; Key Laboratory of Evidence Based Medicine and Knowledge Translation of Gansu Province; No. 199, Donggang West Road Lanzhou City Gansu China 730000
3. Lanzhou University; The Second Clinical Medical College; Lanzhou China
4. Lanzhou University; The First Clincal Medical College; Lanzhou China