P1-S2.49 Chlamydia and gonorrhoea transmission among men who have sex with men in Amsterdam, is independent of network factors or partnership characteristics

BackgroundPartnerships are essential for transmission of sexually transmitted infections (STI). Among MSM, variation in partnerships is common. We have analysed risk factors for STI by studying partnerships.MethodsThe study population was recruited from the STI outpatient clinic of the public health service of Amsterdam, the Netherlands. Inclusion criteria were male gender, having had sexual contact with men in the past 6 months, age ≥18 years, and understanding of written Dutch or English. Recruitment occurred from July 2008 to August 2009. Participants were screened for chlamydia (CT), gonorrhoea (NG), syphilis, and HIV (opting-out strategy). Participants completed a questionnaire including demographics and detailed questions about sexual behaviour in self-defined relationships with a steady partner and the last three other partners within the previous 6 months. Logistic regression analysis was used to identify risk factors for CT and NG.Results2731 MSM reporting 7397 partnerships were included; median age was 39 years (IQR 31–45). CT prevalence was 12.5% (n=342), NG prevalence was 11.1% (n=303), and CT/NG coinfection was found in 2.6% (n=71) of the MSM. Meeting partners online was common (53% met at least one of the partners online), but not associated with STI (CT—OR 1.2 95% CI 0.95 to 1.5 and NG—OR 1.2 95% CI 0.9 to 1.5), just as having concurrent partnerships (CT—OR 3.2 95% CI 0.4 to 23.6 and NG—OR 1.3 95% CI 0.3 to 5.6). In multivariable analysis, independent predictors of CT were having =5 known partners in the last 6 months (OR 1.7 95% CI 1.2 to 2.3), receptive unprotected anal intercourse (OR 2.1 95% CI 1.5 to 2.8), NG coinfection (OR 2.0 95% CI 1.5 to 2.8), and HIV coinfection (OR 1.8 95% CI 1.4 to 2.4). Independent predictors of NG were group sex (OR 1.5 95% CI 1.1 to 2.1), being in a different 10-year age category than the partner (OR 1.4 95% CI 1.04 to 1.8), CT coinfection (OR 2.1 95% CI 1.5 to 2.8), and HIV coinfection (2.2 95% CI 1.6 to 2.9). Age =45 years (OR 0.4 95% CI 0.2 to 0.6) and being bear type (OR 0.4 95% CI 0.2 to 0.9) were associated with lower NG risk.ConclusionsCT and NG infections are associated with positive HIV status and other STI coinfections. We confirmed the association between NG and CT and several known risk factors of the index patient; surprisingly, none of the partnership factors (eg, concurrency, meeting place, or partner's HIV status) , except age difference, were associated with NG or CT.