Over the past decade in the UK, HIV incidence has been increasing among men who have sex with men (MSM). One proposed reason is a recent rise in “chemsex”: the use of drugs to increase sexual disinhibition and arousal. This has the potential to increase the risk of transmission of HIV and other sexually transmitted infections (STIs). We used a nationally-representative survey to determine the prevalence of, and risk factors for, chemsex in HIV-positive MSM in the UK.
Data were collected as part of the Positive Voices study, a cross-sectional survey, conducted in people attending 30 UK HIV clinics from May – November 2014. Responses were linked to clinical data from national surveillance records and weighted to be representative of the national HIV population accessing care. Analyses were restricted to sexually active MSM. Using multivariable analysis, we assessed factors associated with chemsex, and associations between chemsex and unprotected anal intercourse (UAI), UAI with partners of negative or unknown HIV status (sdUAI), multiple casual partnerships, and diagnosis with an STI or hepatitis C.
Of a total 526 MSM responses (39% response rate), 387 (74%) had been sexually active in the previous year. Of these, 29% (95% CI: 21-39%) had engaged in chemsex in the previous year. The most commonly reported chemsex drugs were MCAT (23%; 95% CI: 15-32%), GHB/GBL (20%; 95% CI: 14-27%), and crystal meth (15%; 95% CI: 11-22%). Chemsex was independently associated with being aged 35 to 54, living in London, smoking, diagnosed depression/anxiety, and drug use outside of sex (Table 1). MSM who practiced chemsex had significantly higher odds of engaging in UAI (91% vs. 62%; AOR: 5.3; 95% CI: 1.9-15) and sdUAI (44% vs. 27%; AOR: 2.0; 95% CI: 1.04-3.9) in the previous year, of diagnosis with an STI (71% vs. 39%; AOR: 3.4; 95%CI: 1.7-6.8) and hepatitis C (23% vs. 3.8%; AOR: 6.1; 95% CI: 2.0-18), and had more casual partners in the past year (mean: 33 vs. 8.3; difference: +17; 95% CI: 12-22).
A quarter of HIV-positive MSM reported chemsex, which was associated with increased risky sexual behaviours and STI and hepatitis C diagnosis. This is the first nationally representative study to show this association and highlights the need for funding of interventions to address the risk of HIV and STI transmission among MSM combining drugs with sex.