[1] Sichuan Univ, West China Hosp, Hlth Management Ctr, Gen Practice Ctr, Chengdu, Peoples R China
[2] Haisco Pharmaceut Grp, Data Management & Stat Dept, Biostat Grp, Chengdu, Peoples R China
[3] Sichuan Univ, West China Hosp, Dept Resp & Crit Care Med, Chengdu, Peoples R China
[4] Sichuan Univ, West China Hosp, Dept Geriatr, Guoxuexiang 37, Chengdu 610041, Sichuan, Peoples R China
[5] Sichuan Univ, West China Hosp, Natl Clin Res Ctr Geriatr, Guoxuexiang 37, Chengdu 610041, Sichuan, Peoples R China
[6] New York Med Coll, Sch Hlth Sci & Practice, Dept Publ Hlth, Valhalla, NY USA
[7] Oregon State Univ, Sch Biol & Populat Hlth Sci, Corvallis, OR USA