title: Age-Specific prevalence of anal human papillomavirus infection in HIV-negative sexually active men who have sex with men: the EXPLORE study.
abstract: BACKGROUND
  In the United States, anal cancer in men who have sex with men (MSM) is more common than cervical cancer in women. Human papillomavirus (HPV) is causally linked to the development of anal and cervical cancer. In women, cervical HPV infection peaks early and decreases after the age of 30. Little is known about the age-specific prevalence of anal HPV infection in human immunodeficiency virus (HIV)-negative MSM.
  
  
  METHODS
  We studied the prevalence and determinants of anal HPV infection in 1218 HIV-negative MSM, 18-89 years old, who were recruited from 4 US cities. We assessed anal HPV infection status by polymerase chain reaction.
  
  
  RESULTS
  HPV DNA was found in the anal canal of 57% of study participants. The prevalence of anal HPV infection did not change with age or geographic location. Anal HPV infection was independently associated with receptive anal intercourse (odds ratio [OR], 2.0; P<.0001) during the preceding 6 months and with >5 sex partners during the preceding 6 months (OR, 1.5; P<.0001).
  
  
  CONCLUSIONS
  Urban, HIV-negative MSM have a stable, high prevalence of anal HPV infection across all age groups. These results differ substantially from the epidemiologic profile of cervical HPV infection in women. This may reflect differences between these populations with respect to the number of new sex partners after the age of 30 and may explain the high incidence of anal cancer in MSM.
authors.affiliation: Department of Medicine, University of California at San Francisco, California 94143-0654, USA. pvch@itsa.ucsf.edu
authors.forename: Peter V
authors.initials: PV
authors.lastname: Chin-Hong
authors.forename: Eric
authors.initials: E
authors.lastname: Vittinghoff
authors.forename: Ross D
authors.initials: RD
authors.lastname: Cranston
authors.forename: Susan
authors.initials: S
authors.lastname: Buchbinder
authors.forename: Daniel
authors.initials: D
authors.lastname: Cohen
authors.forename: Grant
authors.initials: G
authors.lastname: Colfax
authors.forename: Maria
authors.initials: M
authors.lastname: Da Costa
authors.forename: Teresa
authors.initials: T
authors.lastname: Darragh
authors.forename: Eileen
authors.initials: E
authors.lastname: Hess
authors.forename: Franklyn
authors.initials: F
authors.lastname: Judson
authors.forename: Beryl
authors.initials: B
authors.lastname: Koblin
authors.forename: Maria
authors.initials: M
authors.lastname: Madison
authors.forename: Joel M
authors.initials: JM
authors.lastname: Palefsky
mesh_terms: D000328:Adult; D000367:Age Factors; D001003:Anal Canal / Q000821:virology*; D001004:Anus Diseases / Q000453:epidemiology* / Q000821:virology; D018023:HIV Seronegativity; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D008875:Middle Aged; D027383:Papillomaviridae / Q000302:isolation & purification*; D030361:Papillomavirus Infections / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors; D014481:United States / Q000453:epidemiology