[1] Guangdong Med Univ, Huizhou Cent Peoples Hosp, Res Ctr, 41 Eleng North Rd, Huizhou, Guangdong, Peoples R China
[2] Benedictine Univ, Sch Publ Hlth, Lisle, IL USA
[3] Chongqing Publ Hlth Med Ctr, Dept Resp, Chongqing, Peoples R China
[4] Harvard Med Sch, Dept Neurosurg, Brigham & Womens Hosp, Boston, MA 02115 USA
[5] Guangdong Med Univ, Huizhou Cent Peoples Hosp, Dept Adm, 41 Eleng North Rd, Huizhou, Guangdong, Peoples R China