[1] Sichuan Univ, W China Hosp, Dept Geriatr, Sichuan, Peoples R China
[2] Second Peoples Hosp Chengdu, Dept Geriatr, Chengdu, Peoples R China
[3] Sichuan Univ, W China Hosp, Dept Clin Epidemiol, Sichuan, Peoples R China
[4] Sichuan Univ, W China Hosp, Dept Infect Dis, Sichuan, Peoples R China
[5] Sichuan Univ, W China Hosp, Digest Syst Dept, Sichuan, Peoples R China