title: Factors associated with unprotected anal sex with multiple non-steady partners in the past 12 months: results from the European Men-Who-Have-Sex-With-Men Internet Survey (EMIS 2010).
abstract: BACKGROUND
  Practising unprotected anal intercourse (UAI) with high numbers of partners is associated with increased risk for acquiring and transmitting HIV and other sexually transmitted infections. Our aim was to describe factors associated with UAI with multiple partners in a large sample of MSM from 38 European countries recruited for an online survey in 2010.
  
  
  METHODS
  Data are from the European Men-Who-Have-Sex-With-Men Internet Survey (EMIS). The analysis was restricted to men who reported any anal sex with a non-steady partner in the past 12 months, and who were either never diagnosed with HIV, or who had been diagnosed with HIV more than 12 months ago, reported a detectable viral load and did not exclusively serosort (n = 91,477). Multivariable logistic regression was used to compare men reporting UAI with four or more (4+) non-steady partners to two comparison groups: a) no UAI with non-steady partners, and b) UAI with 1-3 non-steady partners.
  
  
  RESULTS
  Overall, 9.6% of the study population reported UAI with 4+ partners in the past 12 months. In both models, factors consistently associated with this behaviour were: having been diagnosed with HIV, lower educational levels, use of nitrite inhalants, drugs associated with sex and parties, or erectile dysfunction drugs in the past 4 weeks, using sex-on-site venues in the past 4 weeks, buying or selling sex in the past 12 months, having experienced physical violence due to sexual attraction to men in the past 12 months, reporting sexual happiness, being out to all or almost all of one's acquaintances, and knowing that ART reduces HIV transmissibility.
  
  
  CONCLUSIONS
  Effective antiretroviral treatment drastically reduces HIV transmission for men diagnosed with HIV, irrespective of partner numbers. Apart from reducing partner numbers or increasing condom use no other recommendations are currently in place to reduce the risk of HIV acquisition and onward transmission for HIV-negative men practicing UAI with multiple partners. A range of factors were identified as associated with UAI with four or more partners which allow the strengthening and targeting of prevention strategies to reduce HIV transmission risks resulting from condomless anal intercourse with multiple partners.
authors.affiliation: Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany. sarah.kramer.374@gmail.com.
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Kramer
authors.affiliation: Sigma Research, Department of Social and Environmental Health Research, London School of Hygiene & Tropical Medicine, 15-17 Tavistock Place, WC1H 9SH, London, UK. axel.j.schmidt@emis-project.eu.
authors.forename: Axel Jeremias
authors.initials: AJ
authors.lastname: Schmidt
authors.affiliation: Department of Evidence-Based Health Services, Norwegian Knowledge Center for the Health Services, Oslo, Norway. Rigmor.Berg@kunnskapssenteret.no.
authors.forename: Rigmor C
authors.initials: RC
authors.lastname: Berg
authors.affiliation: HIV & STI Department, Centre for Infectious Disease Surveillance and Control, Public Health England, London, UK. furemiao@gmail.com.
authors.forename: Martina
authors.initials: M
authors.lastname: Furegato
authors.affiliation: University College Maastricht, Maastricht University, Maastricht, The Netherlands. h.hospers@maastrichtuniversity.nl.
authors.forename: Harm
authors.initials: H
authors.lastname: Hospers
authors.affiliation: Centre for Sexually Transmitted Infection and AIDS Epidemiological Studies of Catalonia (CEEISCAT), Barcelona, Spain. cfolch@iconcologia.net.
authors.forename: Cinta
authors.initials: C
authors.lastname: Folch
authors.affiliation: Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany. MarcusU@rki.de.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Marcus
mesh_terms: D000328:Adult; D017280:Condoms / Q000706:statistics & numerical data; D004522:Educational Status; D005060:Europe; D015658:HIV Infections / Q000517:prevention & control*; D018451:Homosexuality, Male / Q000706:statistics & numerical data*; D006801:Humans; D020407:Internet; D016015:Logistic Models; D008297:Male; D011477:Sex Work / Q000706:statistics & numerical data; D012725:Sexual Behavior / Q000706:statistics & numerical data*; D012747:Sexual Partners; D019966:Substance-Related Disorders / Q000453:epidemiology; D011795:Surveys and Questionnaires; D047568:Unsafe Sex / Q000706:statistics & numerical data*; D014754:Violence / Q000706:statistics & numerical data