Chemsex is not a barrier to self-reported daily PrEP adherence among PROUD study participants

Charlotte O'Halloran*, Brian Rice, Ellen White, Monica Desai, David T Dunn, Sheena McCormack, Ann K. Sullivan, David White, Alan McOwan, Mitzy Gafos

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Background: Pre-exposure prophylaxis (PrEP) is a novel HIV prevention method whereby HIV-negative individuals take the drugs tenofovir and emtricitabine to prevent HIV acquisition. Optimal adherence is critical for PrEP efficacy. Chemsex describes sexual activity under the influence of psychoactive drugs, in the UK typically; crystal methamphetamine, gamma-hydroxybutyrate(GHB) and/or mephedrone. Chemsex drug use has been associated with increased HIV transmission risk among gay, bisexual and other men who have sex with men (GBM) and poor ART adherence among people living with HIV. This study assessed whether self-reported chemsex events affected self-reported daily PrEP adherence among PROUD study participants. Methods: The PROUD study was an open-label, randomised controlled trial, conducted in thirteen English sexual health clinics, assessing effectiveness of Truvada-PrEP among 544 HIV-negative GBM. The study reported an 86% risk-reduction of HIV from daily PrEP. Participants were asked about chemsex engagement at follow-up visits. Monthly self-reports of missed PrEP tablets were aggregated to assess adherence between visits. Univariable and multivariable regression analyses were performed to test for associations between chemsex and reporting less than seven out of seven intended doses(<7/7ID) in the 7 days before and/or after last condomless anal intercourse(CAI). Results: 1479 follow-up visit forms and 2260 monthly adherence forms from 388 participants were included in the analyses, with 38.5% visit forms reporting chemsex since last visit and 29.9% follow-up periods reporting <7/7ID. No statistically significant associations were observed between reporting <7/7ID and chemsex (aOR=1.29 [95% CI 0.90–1.87], p = 0.168). Statistically significant associations were seen between reporting <7/7ID and participants perceiving that they would miss PrEP doses during the trial, Asian ethnicity, and reporting unemployment at baseline. Conclusions: These analyses suggest PrEP remains a feasible and effective HIV prevention method for GBM engaging in chemsex, a practise which is prevalent in this group and has been associated with increased HIV transmission risk.

Original languageEnglish
Pages (from-to)246-254
Number of pages9
JournalInternational Journal of Drug Policy
Publication statusPublished - Dec 2019

Bibliographical note

Funding Information:
The PROUD trial was supported by ad hoc funding from the Medical Research Council (MRC) Clinical Trials Unit at University College London and an innovations grant from Public Health England, and most clinics received support through the UK NIHR Clinical Research Network. Gilead Sciences provided Truvada, distributed drug to clinics, and awarded a grant for the additional diagnostic tests including drug concentrations in plasma. EW, DTD and SMc were supported by the UK Medical Research Council ( MC_UU_12,023/23 ) during preparation of and outside the submitted work.

Funding Information:
The PROUD data is held at MRC CTU at UCL, which encourages optimal use of data by employing a controlled access approach to data sharing, incorporating a transparent and robust system to review requests and provide secure data access consistent with the relevant ethics committee approvals. All requests for data are considered and can be initiated by contacting The basis for this project originated from a MSc research project undertaken by COH at the London School of Hygiene & Tropical Medicine (LSHTM), and ethical approval for this MSc project was granted by LSHTM. Data was accessed from University College London (UCL) and the Medical Research Council (MRC) Clinical Trials Unit (CTU) through a clinical data disclosure agreement and PROUD sub-study proposal agreement.

Funding Information:
The PROUD study provided drug free of charge by Gilead Sciences plc. which also distributed it to participating clinics and provided funds for additional diagnostic tests for HCV and drug levels. SMc reports grants from the European Union H2020 scheme, EDCTP 2, the National Institute of Health Research, and Gilead Sciences; other support from Gilead Sciences, and the Population Council Microbicide Advisory Board; and is Chair of the Project Advisory Committee for USAID grant awarded to CONRAD to develop tenofovir-based products for use by women (non-financial). EW university fees and stipend funded by Gilead Science plc. The remaining authors have no competing interests to declare.


  • Adherence
  • Chemsex
  • Gay, bisexual and other men who have sex with men (GBM)
  • HIV
  • Pre-exposure prophylaxis (PrEP)
  • Prevention


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