[1] Sichuan Univ, W China Hosp, Dept Geriatr, Chengdu 610041, Sichuan, Peoples R China
[2] Yanan Univ, Affiliated Hosp, Coll Med, Yanan, Peoples R China
[3] Sichuan Univ, W China Hosp, Dept Pathol, Chengdu 610041, Sichuan, Peoples R China
[4] W China Hosp, Dept Gerontol, Chengdu, Peoples R China
[5] Sichuan Univ, W China Hosp, Chinese Cochrane Ctr, Chinese EBM Ctr, Chengdu 610041, Sichuan, Peoples R China