20th International AIDS Conference - Melbourne, Australia


WEPE123 - Poster Exhibition

Event-level analysis of multipartner sexual encounters: situational characteristics and sexual outcomes reported by MSM in England

G.J. Melendez-Torres1,2, F. Hickson3, D. Reid3, P. Weatherburn3, C. Bonell2

1Centre for Evidence-Based Intervention, Department of Social Policy and Intervention, University of Oxford, Oxford, United Kingdom, 2Social Science Research Unit, Institute of Education, University of London, London, United Kingdom, 3Sigma Research, London School of Hygiene and Tropical Medicine, London, United Kingdom

Background: Digital communication and urban socio-sexuality make multipartner sexual encounters increasingly easy to facilitate, while rising HIV incidence and prevalence of unprotected anal intercourse (UAI) in men who have sex with men (MSM) suggest an emerging risk milieu. Yet few event-level studies examine multipartner encounters, and none address MSM in England or the United Kingdom generally. Moreover, event-level analyses generally do not examine sexual outcomes beyond HIV risk. This analysis tests whether situational characteristics predict UAI, pleasure, and control in a sample of multipartner encounters reported by MSM in England.
Methods: MSM in England participated in a web-based survey throughout 2011 and early 2012 in which they reported up to three multipartner encounters with men. Generalised estimating equations with exchangeable correlation matrices and canonical link functions tested whether number of male participants, respondent substance use, sex venue, and serodiscordance predicted UAI, self-reported control over personal outcomes (yes/no), and pleasure (1-10, with 10 best).
Results: 321 MSM reported 438 encounters. In univariate models, any substance use (OR=1.73, p< 0.05), number of substances used (OR=1.24, p< 0.001), erectile dysfunction medication (OR=2.23, p< 0.05) and crystal methamphetamine (OR=3.18, p< 0.05) use, and not knowing partners'' serostatuses (OR=0.39, p< 0.001)?but not place of sex or number of partners?were significantly associated with engagement in UAI. Effects were similar in multivariate models.

In univariate models testing associations with pleasure, number of substances used (beta=0.14, p< 0.01), number of partners (beta=0.05, p< 0.01), outdoors location (beta=-1.02, p< 0.001), and not knowing partners'' serostatuses (beta=-0.38, p< 0.05), but not any or specific substance use, were statistically significant. Except for serodiscordance, effects significant in univariate models remained significant in multivariate models.

No situational characteristics, except crystal methamphetamine use (OR=0.15, p< 0.001), were associated with reduced control.
Conclusions: This event-level analysis is among the first to examine either multipartner encounters, or sexual outcomes beyond UAI. Situational characteristics?including substance use?that predict sexual risk and pleasure do not predict control, suggesting that in the context of multipartner encounters, control may not mediate the relationship between substance use and sexual risk. Further research should investigate additional situational characteristics and compare encounters within respondents.

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