Calendar trends in sexual behaviours in a cohort of HIV-infected MSM at the era of treatment as prevention of HIV infection

With the advent of treatment as prevention of HIV infection (TasP), we assessed trends in sexual behaviours between 2000 and 2017 among HIV-infected MSM enrolled in the French ANRS PRIMO cohort. At each cohort visit, a clinical questionnaire including laboratory values was completed and a self-administered questionnaire was used to collect sexual behaviours, that is, the number, type (steady/casual) and HIV status (positive or negative/unknown) of partners, and condom use. The possible influence of viral load (undetectable/detectable) measured at the preceding visit on the evolution over time of sexual behaviour was assessed with logistic regression models fitted by generalized estimating equations (GEE), taking into account longitudinal data. We analyzed data from 10657 follow-up visits by 1364 MSM. Overall, whatever the considered behavioural variable: at least one sexual partner, steady and/or casual, condomless sex with steady, casual partners, serodiscordant or not, we observed a calendar increase with a particularly more marked rise from 2010 (P < 0.0001). Inconsistent condom use did not differ according to the viral load status (detectable vs. undetectable). Trends in inconsistent condom use increased across different generations of MSM, as defined by the year they were diagnosed with HIV infection. 'Having a sexual partner' and condomless sex, both increased in frequency between 2000 and 2017. Viral load status did not influence condom use as could have been expected from the 2008 Swiss Statement.