Changes in chemsex and sexual behaviour over time, among a cohort of MSM in London and Brighton: Findings from the AURAH2 study.

BACKGROUND: Recent evidence has suggested that chemsex (the use of mephedrone, crystal methamphetamine and γ -hydroxybutyrate/ γ -butryolactone (GHB/GBL) to enable, enhance and prolong sexual interactions) has increased among men having sex with men (MSM) attending sexual health clinics in large UK cities. To date there has been no data from the UK or Europe that describes changes in chemsex over time within a cohort of MSM.

METHODS: The prospective cohort study, Attitudes to and Understanding Risk of Acquisition of HIV over Time (AURAH2), collected online questionnaire data from HIV negative or undiagnosed MSM (at enrolment) from 2015 to 2018, recruited from sexual health clinics. We aim to investigate changes in chemsex, three individual drugs associated with chemsex, frequency of chemsex sessions and measures of sexual behaviour, among the cohort of MSM over the study's 3 year follow-up period.

RESULTS: In total 622 MSM completed at least one online questionnaire for the AURAH2 study, of which 400 (64.3%) were still engaged with the study within the last six months of follow-up. Prevalence of chemsex significantly declined during the follow-up from 31.8% (198/622) at the first online questionnaire, to 11.1% (8/72; p < 0.001) at the 9th. This decline was reflected in the proportion of MSM reporting use of two of the three individual chemsex drugs: mephedrone use had significantly declined from 25.2% at the first online questionnaire to 9.7% (p < 0.001) at the 9th, GHB/GBL use had also declined from 19.9% to 8.3% (p = 0.001). While crystal methamphetamine use declined, but not significantly (11.1%-6.9% [p = 0.289]). Most measures of sexual behaviour (any anal sex, group sex, recent HIV test and bacterial STI) also tended to decline over the follow-up period, with the exception of CLAI with more than one and more than two partners.

CONCLUSIONS: Chemsex and use of two individual chemsex drugs (mephedrone and GHB/GBL) significantly declined over time among individuals in the study, alongside most measures of sexual behaviour with the exception of those related to CLAI. Focusing health promotion and HIV prevention, such as awareness of post-exposure prophylaxis (PEP) and access to pre-exposure prophylaxis (PrEP), on MSM that report chemsex, and in particular problematic chemsex, would be highly beneficial, potentially only necessary for a relatively short period of time for individuals, and could have long term benefits for HIV and STI prevention.