[1] Harbin Med Univ, Coll Publ Hlth, Dept Epidemiol, 157 Baojian Rd, Harbin 150081, Heilongjiang, Peoples R China
[2] Xuzhou Med Univ, Sch Publ Hlth, Dept Biostat, Xuzhou 221004, Peoples R China
[3] Harbin Med Univ, Canc Hosp, Dept Colorectal Surg, 150 Haping Rd, Harbin 150081, Heilongjiang, Peoples R China