1. Department of Periodical Press and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
2. Chinese Evidence-based Medicine Center, West China Hospital, Sichuan University, Chengdu, P.R. China
3. West China School of Medicine, Sichuan University, Chengdu, P.R. China