title: The importance of partnership factors and individual factors associated with absent or inconsistent condom use in heterosexuals: a cross-sectional study.
abstract: OBJECTIVE
  Decisions to use condoms are made within partnerships. We examined the associations between inconsistent or no condom use and individual and partnership characteristics. We also examined the relative importance of individual versus partnership factors.
  
  
  METHODS
  Cross-sectional study of heterosexual individuals enrolled from the sexually transmitted infections (STI) outpatient clinic in Amsterdam, the Netherlands, from May to August 2010. Participants completed a questionnaire about sexual behaviour with the last four partners in the preceding year. Participant and partnership factors associated with inconsistent or no condom use in steady and casual partnerships were identified.
  
  
  RESULTS
  2144 individuals were included, reporting 6401 partnerships; 54.7% were female, the median age was 25 (IQR 22-30) years and 79.9% were Dutch. Inconsistent or no condom use occurred in 86.1% of 2387 steady partnerships and in 66.5% of 4014 casual partnerships. There was statistical evidence of associations between inconsistent condom use in steady partnerships and ethnic concordance, longer duration, higher number of sex acts, practising anal sex, and sex-related drug use. In casual partnerships, associations were found with having an older partner, ethnic concordance, longer duration, higher number of sex acts, anal sex, sex-related drug use, ongoing partnerships and concurrency. In multivariable models, partnership factors explained 50.9% of the variance in steady partnerships and 70.1% in casual partnerships compared with 10.5% and 15.4% respectively for individual factors.
  
  
  CONCLUSIONS
  Among heterosexual STI clinic attendees in Amsterdam, partnership factors are more important factors related with inconsistent condom use than characteristics of the individual.
authors.affiliation: Cluster of Infectious Diseases, Public Health Service of Amsterdam, Amsterdam, The Netherlands Julius Centre for Health Sciences & Primary Care, University Medical Centre Utrecht (UMCU), Utrecht, The Netherlands.
authors.forename: Amy
authors.initials: A
authors.lastname: Matser
authors.affiliation: Cluster of Infectious Diseases, Public Health Service of Amsterdam, Amsterdam, The Netherlands Center for Infection and Immunology Amsterdam (CINIMA), Academic Medical Center (AMC), Amsterdam, The Netherlands.
authors.forename: Marlies
authors.initials: M
authors.lastname: Heiligenberg
authors.affiliation: Cluster of Infectious Diseases, Public Health Service of Amsterdam, Amsterdam, The Netherlands Department of Clinical Epidemiology, Biostatistics and Bioinformatics, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Ronald
authors.initials: R
authors.lastname: Geskus
authors.affiliation: Cluster of Infectious Diseases, Public Health Service of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Titia
authors.initials: T
authors.lastname: Heijman
authors.affiliation: Division of Clinical Epidemiology & Biostatistics, Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland.
authors.forename: Nicola
authors.initials: N
authors.lastname: Low
authors.affiliation: Julius Centre for Health Sciences & Primary Care, University Medical Centre Utrecht (UMCU), Utrecht, The Netherlands Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
authors.forename: Mirjam
authors.initials: M
authors.lastname: Kretzschmar
authors.affiliation: Cluster of Infectious Diseases, Public Health Service of Amsterdam, Amsterdam, The Netherlands Center for Infection and Immunology Amsterdam (CINIMA), Academic Medical Center (AMC), Amsterdam, The Netherlands.
authors.forename: Maarten Schim
authors.initials: MS
authors.lastname: van der Loeff
mesh_terms: D000328:Adult; D000367:Age Factors; D017280:Condoms / Q000706:statistics & numerical data*; D003430:Cross-Sectional Studies; D005260:Female; D020010:Heterosexuality / Q000706:statistics & numerical data*; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D012307:Risk Factors; D012747:Sexual Partners; D011795:Surveys and Questionnaires; D047568:Unsafe Sex / Q000208:ethnology / Q000706:statistics & numerical data*; D055815:Young Adult
keywords: Condom; Partnership; Sexually transmitted diseases; Unsafe sex