[1] Second Peoples Hosp, Dept Resp Med, Neijiang 641199, Sichuan, Peoples R China
[2] Chinese Med Hosp, Dept First Internal Med, Neijiang 641099, Sichuan, Peoples R China
[3] First Peoples Hosp, Dept Geriatr Resp & Crit Med, Neijiang 641000, Sichuan, Peoples R China
[4] Chinese Med Hosp, Dept Resp Med, Neijiang 641099, Sichuan, Peoples R China
[5] Chengdu Aerosp Hosp, Dept Resp Med, Chengdu 610199, Sichuan, Peoples R China
[6] Nanchong Cent Hosp, Dept Oncol, Nanchong 637900, Sichuan, Peoples R China