[1] Cent South Univ, Xiangya Sch Publ Hlth, Dept Social Med & Hlth Management, 238 Shangmayuanling Rd, Changsha 410078, Hunan, Peoples R China
[2] Guizhou Minzu Univ, Coll Data Sci & Informat Engn, Guiyang, Guizhou, Peoples R China
[3] Cent South Univ, Xiangya Sch Publ Hlth, Dept Epidemiol & Hlth Stat, Changsha, Hunan, Peoples R China
[4] Mzuzu Univ, Dept Math & Stat, Luwinga, Malawi