Abstract Body

Men who have sex with men (MSM) constitute a high-risk group in France’s HIV epidemic. In the setting of the follow-up in the ANRS IPERGAY PrEP trial, we aimed to identify behavioural trajectories over time for PrEP and condom use and to investigate links between these trajectories, using a tailored methodological framework.

ANRS IPERGAY was a randomized double-blind trial of sexual activity-based PrEP in high-risk MSM, assigned to TDF-FTC or placebo. Online questionnaires collecting sexual behaviour and PrEP adherence data during the most recent episode of sexual intercourse were completed every 2 months. Only MSM reporting anal sex were included in this analysis. A longitudinal multi-trajectory model was constructed for two outcomes: PrEP use (correct/sub-optimal versus no PrEP), and condom use for anal sex (yes/no). Multivariate analyses were performed on identified trajectories using sociodemographic, socioeconomic, and behavioural data.

332 participants (47.9% placebo; 52.1% PrEP) who had anal sex at least once during follow-up provided information on PrEP (1115 questionnaires) and/or condom (1935 questionnaires) use during the most recent episode of sexual intercourse. Four trajectories of PrEP use over time were identified among participants: “systematic users (PrEP-SU)” (39.5%), “high-level progressive users (PrEP-HLU)” (31.1%), “declining users (PrEP-DU)” (13.3%), and “low-level users (PrEP-LLU)” (16.1%). For condom use, common behaviour patterns identified two groups: “high-level users (C-HLU)” (29.9%) and “low-level users (C-LLU)” (70.1%). Joint trajectory modelling identified four groups: among C-HLU, 78% were PrEP-SU/PrEP-HLU, while 22% were PrEP-DU/PrEP-LLU. Among C-LLU, 68% were PrEP-SU/PrEP-HLU, whereas 32% were PrEP-DU/PrEP-LLU. The latter group (most-at-risk group), compared most protected group (C-HLU/PrEP-SU) included more frequently older participants (OR=1.05 per each additional year, p<0.001) with low-education levels (OR=1.91, p=0.02, ref. ≥ high school), participants with unknown partners (OR=2.82, p<0.001), those sexually dissatisfied (OR=2.09, p<0.001), and a trend appears for those practicing active anal sex (vs. receptive, p=0.08).

In the ANRS IPERGAY trial, most high-risk MSM used either PrEP and/or condoms during the most recent anal intercourse. Special attention must be paid to MSM with low condom use who do not compensate by using PrEP, representing 22% among the 332 participants included in this analysis.