[1] China Med Univ, Dept Gen Practice, Affiliated Hosp 1, 155 Nanjing North St, Shenyang 110001, Liaoning Provin, Peoples R China
[2] China Med Univ, Sci Expt Ctr, Shenyang, Peoples R China
[3] China Med Univ, Dept Epidemiol, Coll Publ Hlth, Shenyang, Peoples R China