title: Semen says: assessing the accuracy of adolescents' self-reported sexual abstinence using a semen Y-chromosome biomarker.
abstract: Researchers often assess condom use only among participants who report recent sexual behaviour, excluding participants who report no recent vaginal sex or who did not answer questions about their sexual behaviour, but self-reported sexual behaviour may be inaccurate. This study uses a semen Y-chromosome biomarker to assess semen exposure among participants who reported sexual abstinence or did not report their sexual behaviour.
  
  
  
  This prospective cohort study uses data from 715 sexually active African-American female adolescents in Atlanta, surveyed at baseline, 6 months and 12 months. Participants completed a 40 min interview and were tested for semen Y-chromosome with PCR from a self-administered vaginal swab. We predicted Y-chromosome test results from self-reported sexual behaviour using within-subject panel regression.
  
  
  
  Among the participants who reported abstinence from vaginal sex in the past 14 days, 9.4% tested positive for semen Y-chromosome. Among item non-respondents, 6.3% tested positive for semen Y-chromosome. Women who reported abstinence and engaged in item non-response regarding their sexual behaviour had respectively 62% and 78% lower odds of testing positive for Y-chromosome (OR 0.38 (0.21 to 0.67), OR 0.22 (0.12 to 0.40)), controlling for smoking, survey wave and non-coital sexual behaviours reported during abstinence.
  
  
  
  Adolescents who report sexual abstinence under-report semen exposure. Research should validate self-reported sexual behaviour with biomarkers. Adolescents who engage in item non-response regarding vaginal sex test positive for semen Y-chromosome at similar rates, which supports the practice of grouping non-respondents with adolescents reporting abstinence in statistical analysis.
  
  
  
  NCT00633906.
authors.affiliation: Department of Epidemiology, School of Public Health, SUNY Downstate Medical Center, Brooklyn, New York, USA.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Rosenbaum
authors.affiliation: Department of Infectious Diseases, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Zenilman
authors.affiliation: Behavioural Sciences and Health Education, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA.
authors.forename: Eve
authors.initials: E
authors.lastname: Rose
authors.affiliation: Behavioural Sciences and Health Education, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA.
authors.forename: Gina M
authors.initials: GM
authors.lastname: Wingood
authors.affiliation: Behavioural Sciences and Health Education, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA.
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: DiClemente
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D001741:Black or African American / Q000706:statistics & numerical data; D015415:Biomarkers / Q000032:analysis; D041322:Chromosomes, Human, Y / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D057566:Self Report; D012661:Semen / Q000737:chemistry*; D012746:Sexual Abstinence / Q000706:statistics & numerical data*; D012725:Sexual Behavior / Q000706:statistics & numerical data*; D014481:United States; D014621:Vagina / Q000737:chemistry*
chemical_list: D015415:Biomarkers
keywords: ADOLESCENT; EPIDEMIOLOGY (GENERAL); HETEROSEXUAL BEHAVIOUR; SEXUAL BEHAVIOUR; WOMEN