Chemsex and incidence of sexually transmitted infections among Canadian pre-exposure prophylaxis (PrEP) users in the l'Actuel PrEP Cohort (2013-2020).

OBJECTIVES: Use of illicit substances during sex (chemsex) may increase transmission of HIV and other STIs. Pre-exposure prophylaxis (PrEP) is highly effective at preventing HIV transmission, providing an important prevention tool for those who practise chemsex. However, it does not prevent acquisition of other STIs. We aim to examine the impact of chemsex on STI incidence among gay, bisexual and other men who have sex with men (gbMSM), and transgender women using PrEP in Montréal, Canada. METHODS: We linked baseline sociodemographic and behavioural data with follow-up STI testing from 2013 to 2020 among PrEP users in the l'Actuel PrEP Cohort (Canada). Focusing on the 24 months following PrEP initiation, we estimated the effect of chemsex reported at baseline on cumulative incidence of gonorrhoea and chlamydia using Kaplan-Meier curves and survival analyses. We investigated the role of polysubstance use and effect modification by sociodemographic factors. RESULTS: There were 2086 clients (2079 cisgender gbMSM, 3 transgender gbMSM, 4 transgender women) who initiated PrEP, contributing 1477 years of follow-up. There were no incident HIV infections among clients on PrEP. Controlling for sociodemographic confounders, clients reporting chemsex at baseline had a 32% higher hazard of gonorrhoea/chlamydia diagnosis (adjusted HR=1.32; 95% CI: 1.10 to 1.57), equivalent to a risk increase of 8.9 percentage points (95% CI: 8.5 to 9.4) at 12 months. The effect was greater for clients who reported polysubstance use (adjusted HR=1.51; 95% CI: 1.21 to 1.89). The strength of the effect of chemsex on STI incidence varied by age, education and income. CONCLUSION: Among PrEP users, chemsex at baseline was linked to increased incidence of gonorrhoea and chlamydia. This effect was stronger for people reporting multiple chemsex substances. The high STI incidence among gbMSM who report chemsex highlights the importance of PrEP for this population and the need for integrated services that address the complexities of sexualised substance use.

Characteristics of new HIV diagnoses over 1995-2019: A clinic-based study in Montréal, Canada.

BACKGROUND: Characterization of populations at risk of acquiring HIV is required to inform the public health response to HIV. To identify potential changing needs in HIV prevention and care cascade, we aim to describe how the demographic profiles and exposure categories of newly diagnosed HIV positive individuals attending a large sexual health clinic in Montréal (Canada) evolved since the beginning of the antiretroviral therapy era in the mid-1990s. METHODS: Using diagnosis data from participants of the Clinique médicale l'Actuel cohort of HIV-positive patients, we examined the distribution of exposure categories (sexual orientation, sexual behaviours, injection drug use, being born in an HIV-endemic country) by gender and year of diagnosis. Time trends in mean age and in the proportion of patients with late (CD4 <350 cells/µL) or advanced stage (CD4 <200 cells/µL) of HIV infection at diagnosis were assessed through meta-regressions. RESULTS: A total of 2,612 patients diagnosed with HIV between January 1st, 1995 and December 31st, 2019 were included. Overall, mean age was 35 years (standard deviation: 10 years) and remained stable over time. The proportion of patients with advanced stage of HIV infection decreased from 16% in 1995 to 4% in 2019. Although men who have sex with men (MSM) consistently accounted for the highest proportion of new diagnoses (77%, 2,022/2,612 overall), their proportion decreased since 2013. There was also a concomitant decrease in the proportion of people who inject drugs, with none of the newly diagnosed participants reporting injection drug use since 2017, and an important increase in the proportion of patients born in an HIV-endemic country (24%, 7/29 in 2019), especially among women. Compared to patients from non-endemic countries, those from HIV-endemic countries were characterized by higher proportions of heterosexuals (88% vs 17%) and of women (52% vs 7%), and were twice likely to get diagnosed at an advanced stage of HIV infection (32% vs 15%). CONCLUSIONS: In absolute numbers, MSM continue to account for the largest exposure category. However, patients from HIV-endemic countries, who tend to be diagnosed at later stages of HIV infection, constitute an increasing proportion of newly diagnosed individuals. These persons could face distinct barriers to rapid diagnosis. Tailoring HIV testing strategies and other prevention interventions to the specific unmet prevention needs of these individuals is warranted.

Chemsex practices and pre-exposure prophylaxis (PrEP) trajectories among individuals consulting for PrEP at a large sexual health clinic in Montréal, Canada (2013-2020).

INTRODUCTION: Chemsex among gay, bisexual and other men who have sex with men (gbMSM) has raised public health concerns because of its association with sexual behaviours that can increase transmission of sexually transmitted infections, including HIV. Pre-exposure prophylaxis (PrEP) is highly effective at blocking HIV acquisition, addressing important prevention needs among individuals practicing chemsex. This study aims to improve our understanding of chemsex practices and PrEP trajectories of gbMSM and transgender women consulting for PrEP. METHODS: We used data from the PrEP cohort of Clinique médicale l'Actuel, a major sexual health clinic in Montréal. We describe the sociodemographic profile of clients consulting for PrEP, characterize chemsex and polysubstance use trends over time, and evaluate PrEP trajectories using Kaplan-Meier curves. RESULTS: Among 2923 clients who consulted for PrEP between 2013-2020 (2910 cisgender gbMSM, 6 transgender gbMSM, 7 transgender women), 24 % reported chemsex in the past year and 13 % reported polysubstance use. The most common chemsex substances were ecstasy (14 %), GHB (13 %), and cocaine (12 %). The proportion of clients reporting chemsex and polysubstance use decreased over time. In both the chemsex and no-chemsex group, 73 % of clients initiated PrEP. The median time to discontinuation was similar between the chemsex (6.5 months; 95 %CI: 5.3-7.2) and no-chemsex group (6.9 months; 95 %CI: 6.3-7.5). CONCLUSION: Chemsex is not a barrier to PrEP initiation or persistence. However, these results suggest a high prevalence of chemsex among gbMSM consulting for PrEP, highlighting the need for services addressing the intersection of sexual health and substance use for this population.