[1] Ningxia Med Univ, Yinchuan, Ningxia, Peoples R China
[2] Ningxia Med Univ, Gen Hosp, Yinchuan, Ningxia, Peoples R China
[3] Chinese Ctr Dis Control & Prevent, Beijing, Peoples R China
[4] Ningxia CDCP, Yinchuan, Ningxia, Peoples R China
[5] First Affiliated Hosp Chongqing Med Univ, Chongqing, Peoples R China