1. Emergency Office of West China Hospital, Sichuan University, Chengdu, China
2. Department of Health Policy and Management, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
3. Department of Child Health Care, Sichuan Academy of Medical Sciences and Sichuan Provincial People’s Hospital, Chengdu, China
4. National Survey Research Center National Survey Research Center at Renmin University of China, NSRC, Renmin University of China, Beijing, China.