1. Institute of Social Medicine and Health Administration, School of Public Health, Lanzhou University, Gansu, China
2. Institute of Epidemiology and Statistics, School of Public Health, Lanzhou University, Gansu, China
3. Institute of Occupational and Environmental Health, School of Public Health, Lanzhou University, Gansu, China
4. Evidence-Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Gansu, China
5. Key Laboratory of Evidence Based Medicine and Knowledge Translation of Gansu Province, School of Basic Medical Sciences, Lanzhou University, Gansu, China