City of love: Group sex is associated with risks for HIV and other sexually transmissible infections among gay and bisexual men in Paris, France

This study explored the relationships between participation in group sex and risk for HIV and other sexually transmissible infections (STIs). Methods: An anonymous online survey collected data from 580 gay and bisexual men using a mobile sex and dating application in Paris, France. Logistic regression analyses were conducted, which controlled for HIV status, HIV pre-exposure prophylaxis (PrEP) use and participants' sociodemographic characteristics. Results: Compared with men with no recent group sex experience, those reporting group sex in the 3 months before the survey (30.7% of the sample) were more likely to have had condomless receptive anal sex at least once in the same period [adjusted odds ratio (aOR) = 1.6, 95% confidence interval (CI) = 1.1-2.4, P = 0.02], condomless insertive anal sex (aOR = 2.0, 95%CI: 2.4-8.7, P < 0.001) and substance use before or during sex (aOR = 1.6, 95%CI: 1.1-2.3, P = 0.02). Even when controlling for condom use, men involved with group sex were more likely to be have been diagnosed with a bacterial STI in the previous year (aOR = 2.1, 95%CI: 1.3-3.3, P = 0.002). Conclusions: Group sex remains a useful marker of risk among gay and bisexual men, but research is needed that moves beyond individual practice in order to assess the epidemiological networks comprising group sex and the risks they pose relevant to HIV and other STIs.