[1] Nantong Univ, Evidence Based Med Ctr, Med Sch, Nantong, Jiangsu, Peoples R China
[2] Lianyungang 1 Peoples Hosp, Dept Gastroenterol, Lianyungang, Jiangsu, Peoples R China
[3] Ningxiang Peoples Hosp, Dept Infect Dis, Ningxiang, Hunan, Peoples R China
[4] Harvard Med Sch, Dept Populat Med, Boston, MA 02115 USA
[5] Harvard Pilgrim Hlth Care Inst, Boston, MA USA