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. 2025 Aug 5.
doi: 10.1007/s40121-025-01201-7. Online ahead of print.

Long-Term Health Outcomes of People with HIV Engaged in Chemsex: A Prospective Cohort Study on Drug Use, Sexual Behaviour, Sexually-Transmitted Infections and Vulnerability

Lorena De La Mora #  1 , Montserrat Laguno #  2 , Berta Torres  2 , Ivan Chivite  1 , Alberto Foncillas  1 , Alexy Inciarte  1 , Júlia Calvo  1 , Ana González-Cordón  2 , Juan Ambrosioni  2 , Leire Berrocal  1 , Elisa De Lazzari  2 , Esteban Martínez  2 , José Luís Blanco  2 , Rubén Mora  3 , Estela Solbes  1 , Ana Rodriguez  1 , Pilar Callau  1 , Laia Miquel  4 , Jordi Blanch  4 , Duncan Short  5 , Josep Mallolas #  2 , Maria Martínez-Rebollar #  6
Affiliations

Long-Term Health Outcomes of People with HIV Engaged in Chemsex: A Prospective Cohort Study on Drug Use, Sexual Behaviour, Sexually-Transmitted Infections and Vulnerability

Lorena De La Mora et al. Infect Dis Ther. .

Abstract

Introduction: Chemsex, the intentional use of drugs to enhance sexual experiences among gay, bisexual, and other men who have sex with men (gbMSM), is linked to high-risk sexual behaviours and increased sexually transmitted infections (STIs). Data on its long-term evolution after implementing specific strategies in HIV settings are limited. We evaluated the incidence of drug use, sexual behaviour, STIs, and vulnerabilities over 3 years following a specific approach at the HIV Unit of Hospital Clinic in Barcelona, Spain.

Methods: We included 209 gbMSM living with HIV who engaged in chemsex in a prospective cohort (2018-2022). Quarterly visits assessed sexual behaviours, drug use, and STIs screening. Data were collected via self-administered questionnaires, medical records, and microbiological tests. Statistical analyses included descriptive statistics and Poisson regression models.

Results: Chemsex incidence decreased significantly (IRR 0.88, 95% CI 0.83-0.92, p < 0.001). People engaging in intravenous drug use (slamming) decreased in year 2 (IRR 0.71, 95% CI 0.52-0.98, p = 0.037) but rose non-significantly in year 3 (IRR 0.86, 95% CI 0.60-1.25, p = 0.434). High-risk sexual behaviours persisted, specifically unprotected anal sex (IRR 1.02, 95% CI 0.96-1.08, p = 0.481) and unprotected fisting (IRR 1.20, 95% CI 1.05-1.39, p = 0.010). Syphilis cases declined (IRR 0.40, 95% CI 0.26-0.60, p < 0.001). At baseline, 29% had HCV antibodies, with five new acute HCV cases. Concerns about chemsex decreased (IRR 0.52, 95% CI 0.43-0.63, p < 0.001), whereas the demand for sexuality-related assistance increased (IRR 1.53, 95% CI 1.20-1.94, p = 0.004). Loss to follow-up (21%) was greater among younger individuals, people engaging in intravenous drug use (slamming) (IRR 2.43 95% CI 1.33-4.42, p = 0.004), detectable HIV viral load (IRR 3.01, 95% CI 1.57-5.76, p = 0.001), and greater need for help (IRR 1.35, 95% CI 1.03-1.78, p = 0.03). Migrants and sex workers had higher rates of syphilis, lower education levels, and increased prevalence of STIs.

Conclusion: Chemsex incidence and syphilis rates declined, but persistent high-risk behaviours, subgroup vulnerabilities, and increasing demand for sexuality-related assistance require targeted interventions and comprehensive support.

Keywords: Chemsex; HIV; Long-term follow-up; Vulnerabilities; gbMSM.

Plain language summary

This study investigated chemsex, which refers to the use of drugs to enhance sexual experiences among gay, bisexual, and other men who have sex with men (gbMSM) over 3 years at the HIV Unit of Hospital Clinic in Barcelona, Spain. The goal was to determine how drug use, sexual behaviour, sexually transmitted infections (STIs), and other vulnerabilities changed after the implementation of a specific care approach. The study followed 209 gbMSM living with HIV engaged in chemsex. Every 3 months, the participants completed questionnaires on substance use, sexual behaviours, and concerns, and medical tests were conducted. The results revealed that the number of people engaging in chemsex decreased over time. Most drug use decreased, except for mephedrone, a stimulant drug. Slamming, or injecting drugs in this context, also decreased in the second year but rose slightly in the third year without reaching significant levels. The number of syphilis cases decreased and only a few new cases of hepatitis C were found despite the continuation of risky sexual behaviours. Concerns about engaging in chemsex diminished, although people who still needed help asked for support related to their sexuality. Migrants and sex workers had higher rates of syphilis, lower education levels, and more STIs. Younger people and people who use intravenous drugs were more likely to be lost to follow-up. In conclusion, while the rates of chemsex and syphilis declined, risky sexual behaviours and vulnerabilities remained. More support and targeted health programs are needed to help those facing specific vulnerabilities.

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Conflict of interest statement

Declarations. Conflicts of Interest: Lorena De La Mora has received fees to give lectures from Gilead, MSD, ViiV, AbbVie and Janssen-Cilag. Montserrat Laguno has received fees to give lectures from Gilead, MSD, ViiV, AbbVie and Janssen-Cilag. Maria Martínez-Rebollar has received fees to give lectures from Gilead, MSD, ViiV, AbbVie and Janssen-Cilag. Berta Torres has received fees to give lectures from Gilead, MSD, ViiV, AbbVie and Janssen-Cilag. Juan Amborsioni has participated in advisory boards and received consulting honoraria, research grants, or both from Gilead Sciences, Janssen Pharmaceuticals, and ViiV Healthcare, all outside of this work. Alberto Foncillas has received fees to give lectures from Gilead and ViiV. Esteban Martínez has received honoraria for lectures or advisory boards from Gilead and Janssen, and his institution has received research grants from MSD and ViiV. Laia Miquel has received honoraria for lectures from Lundbeck, Gilead and Neuraxpharm. Jordi Blanch has received honoraria for lectures or advisory boards from Ferrer Internacional, Gilead, Janssen, MSD and ViiV. Ana González-Cordón has received fees to give lectures and participate in advisory boards from Gilead, MSD, ViiV, AbbVie and Janssen-Cilag. Alexy Inciarte has received educational grants from MSD and Gilead. José Luís Blanco has received honoraria for lectures or advisory boards from Gilead, Janssen, MSD. Iván Chivite has received fees to give lectures from Gilead, MSD, ViiV, AbbVie and Janssen-Cilag. Duncan Short is an employee of ViiV Healthcare and a shareholder of GlaxoSmithKline. Josep Mallolas has received honoraria, speakers’ fees, consultant fees or funds for research from MSD, Roche, Boehringer-Ingelheim, ViiV, Gilead, Janssen, BMS, and AbbVie. Estela Solbes has a research grant from Gilead. Elisa De Lazzari, Leire Berrocal, Ana Rodriguez, Pilar Callau, Júlia Calvo and Rubén Mora have nothing to disclose. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. Ethical Approval: The present study adhered to the ethical principles set forth in the Declaration of Helsinki from 1964 and its later amendments and followed all principles of good clinical practice. Ethics approval was previously obtained from the local research ethics committee from Hospital Clínic of Barcelona for the CSC Study (HCB/2017/0909) and funded by an international grant from ViiV Healthcare through its Positive Pathways program. All participants signed an informed consent form consenting to the study and further use of data.

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