1. Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University; Lanzhou, Gansu China
2. Department of Health Research Methods, Evidence, and Impact; McMaster University; Hamilton Canada
3. Social Sciences Research Center, School of Public Health, Lanzhou University; Lanzhou, Gansu China
4. The School of Dental Medicine, Lanzhou University; Lanzhou, Gansu China
5. Department of Hematology; The First Hospital of Lanzhou University; Lanzhou, Gansu China