Differences between men who have sex with men that use drugs and engage in chemsex and those who do not engage in chemsex in the French ANRS-PREVENIR cohort: the need to rethink harm reduction services.

Background: An increasing number of studies are exploring the profiles of men who have sex with men (MSM) in the context of the sexualized use of drugs (chemsex). However, less attention has been paid to MSM who use drugs but do not engage in chemsex. We do not know to what extent the latter are different from the former, or whether they require similar harm reduction services. This study aimed to compare both populations in terms of their sexual risk practices, health, and pre-exposure prophylaxis (PrEP) use.

Methods: We used longitudinal data from the ongoing French cohort study ANRS-PREVENIR, which comprises 3076 MSM receiving PrEP. Analyses were conducted on MSM who engaged in chemsex, MSM who used drugs but did not engage in chemsex, and MSM who did not use drugs. Only persons with available data from at least one follow-up visit between M0 and M36 were included, representing 19,375 visits. We built a three-category outcome: (i) MSM who did not use drugs (non-DU), (ii) MSM who used drugs but did not engage in chemsex (DU), and (iii) MSM who engaged in chemsex (CX). A multinomial logistic functional form was used to estimate odds-ratios and 95% confidence intervals, using the DU category as a reference.

Results: Among the 2493 cohort participants, at baseline, 62.8%, 22.5%, and 14.6% of the participants were classified in the non-DU, DU, and CX categories, respectively. Compared to DU, non-DU were less likely to (i) declare fisting/BDSM practices, (ii) have a moderately risky sex life, ii) report lifetime PrEP use. Compared to DU, CX also had lower alcohol consumption, and were less likely to have (i) a tertiary education qualification, and (ii) a main partner; in contrast, CX were more likely to be depressed. CX were more likely to report fisting/BDSM practices, but less likely not to use PrEP and to report suboptimal PrEP adherence compared to DU participants.

Conclusions: Differences between the DU and CX populations were observed; the latter were more likely to (i) have at-risk sexual practices, (ii) suffer from depression, and (iii) have optimal PrEP adherence. It is essential to provide suitable mental health services to people who engage in chemsex, and to implement tailored sexual health and harm reduction services to MSM who use drugs but who do not engage in chemsex.