title: [The prevalence of HIV infection and the risk factors among MSM in 4 cities, China].
abstract: OBJECTIVE
  To access the prevalence of HIV infection and the associated factors among urban MSM in China.
  
  
  METHODS
  Participants were recruited using respondent driven sampling and snowball sampling method in Beijing, Harbin, Zhengzhou and Chengdu city. A face-to-face questionnaire was administrated to collect relevant demographic and ethological data; 5 ml venous blood sample was taken from each subject to measure HIV antibody in serum (samples were first screened by colloidal gold, latex chromatographic and double-antigen sandwich ELISA method, positive samples were further confirmed by immunoblotting method). The characteristics of HIV infection was described and the risk factors were analyzed.
  
  
  RESULTS
  A total of 1864 MSM were recruited and the prevalence of HIV was 6.7% (125/1864). It was 9.5% (24/252) among MSM older than 39 years and it was 1.9% (2/105) among those less than 20 years old. The prevalence was 8.4% (31/371) among MSM with junior level education and was 4.8% (41/858) among those with college level education. It was 10.3% (35/340) among MSM with sexual partner old than him for over 10 years while it was 5.0% (58/1168) among those having sexual partner within 10 years older. The prevalence of HIV infection was 8.9% (61/695) among MSM with unprotected receptive anal sex and it was 5.5% (64/1169) among those without unprotected receptive anal sex. The risk factors independently associated with HIV infection included being older than 39 years (OR = 6.5, 95%CI: 1.5 - 28.7), with junior or lower level education (OR = 1.8, 95%CI: 1.2 - 2.7), having sexual partner older than himself for over 10 years (OR = 2.1, 95%CI: 1.3 - 3.3) and having unprotected receptive anal intercourse (OR = 1.6, 95%CI: 1.1 - 2.4).
  
  
  CONCLUSIONS
  MSM had a high rate of HIV infection. Older age, lower level education, having older sexual partner and unprotected receptive anal intercourse were related to HIV infection.
authors.affiliation: National Center of AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Xu
authors.forename: De-lin
authors.initials: DL
authors.lastname: Han
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
authors.forename: Xiao-yan
authors.initials: XY
authors.lastname: Ma
authors.forename: Li-li
authors.initials: LL
authors.lastname: Wang
authors.forename: Jie
authors.initials: J
authors.lastname: Xu
authors.forename: Lin
authors.initials: L
authors.lastname: Pang
authors.forename: Hong-bo
authors.initials: HB
authors.lastname: Zhang
authors.forename: Zun-you
authors.initials: ZY
authors.lastname: Wu
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D015658:HIV Infections / Q000453:epidemiology*; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D015995:Prevalence; D012307:Risk Factors; D011795:Surveys and Questionnaires; D055815:Young Adult