title: High prevalence of sexual concurrency and concurrent unprotected anal intercourse across racial/ethnic groups among a national, Web-based study of men who have sex with men in the United States.
abstract: BACKGROUND
  Men who have sex with men (MSM) are the largest human immunodeficiency virus (HIV) risk group in the United States. Sexual concurrency may contribute to high HIV incidence or to racial/ethnic HIV disparities among MSM. Limited information is available on concurrency and racial/ethnic differences among MSM or on the extent to which MSM engage in concurrent unprotected anal intercourse (UAI).
  
  
  METHODS
  Data are from baseline responses in a prospective online study of MSM aged 18 years or older, having 1 or more male sex partners in the past 12 months, and recruited from social networking Web sites. Pairwise sexual concurrency and UAI in the previous 6 months among up to 5 recent partners was measured, using an interactive questionnaire. Period prevalences of concurrency and concurrent UAI were computed and compared across racial/ethnic groups at the individual and triad (a respondent and 2 sex partners) levels.
  
  
  RESULTS
  A total of 2940 MSM reported on 8911 partnerships; 45% indicated concurrent partnerships, and 16% indicated concurrent UAI in the previous 6 months. Respondents were more likely to have UAI with 2 partners when they were concurrent, compared to serially monogamous (odds ratio, 1.93, 95% confidence interval, 1.75-2.14). No significant differences in levels of individual concurrency or concurrency among triads were found between non-Hispanic white, non-Hispanic black, and Hispanic men.
  
  
  CONCLUSIONS
  Concurrency and concurrent UAI in the previous 6 months was common. Although there were no differences by race/ethnicity, the high levels of concurrency and concurrent UAI may be catalyzing the transmission of HIV among MSM in general.
authors.affiliation: Department of Epidemiology, Emory University Rollins School of Public Health, Atlanta, GA 30322, USA. esrose2@emory.edu
authors.forename: Eli S
authors.initials: ES
authors.lastname: Rosenberg
authors.forename: Christine M
authors.initials: CM
authors.lastname: Khosropour
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Sullivan
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D000368:Aged; D006679:HIV Seropositivity / Q000453:epidemiology* / Q000208:ethnology; D054624:Health Status Disparities; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D018451:Homosexuality, Male / Q000208:ethnology* / Q000706:statistics & numerical data*; D006801:Humans; D020407:Internet; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012747:Sexual Partners; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D047568:Unsafe Sex / Q000208:ethnology* / Q000706:statistics & numerical data*; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult