Chemsex and diagnoses of syphilis, gonorrhoea and chlamydia among men who have sex with men in the UK: a multivariable prediction model using causal inference methodology

Louis MacGregor*, Manik Kohli, Katharine J Looker, Ford Hickson, Peter Weatherburn, Axel J Schmidt, Katy Me Turner

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Abstract

INTRODUCTION: In the last decade diagnoses of most STIs have risen among men who have sex with men (MSM). Although a significant proportion of this is likely due to increased STI screening, understanding the role of behavioural drivers remains critical. We measure the associations between stimulant use to enhance and prolong sexual experiences (chemsex) and bacterial STI diagnoses in UK MSM, individually considering HIV-diagnosed MSM, pre-exposure prophylaxis (PrEP) users and other MSM.

METHODS: We used the UK 2017-2018 European MSM Internet Survey data (n=9375). We constructed causal inference models using multivariable logistic regression, calculating adjusted OR (aOR) and 95% CI of the associations between participation in recent (≤12 months) exclusively dyadic or multipartner chemsex versus no chemsex and recent self-reported diagnoses of syphilis, gonorrhoea and chlamydia.

RESULTS: Among MSM with an HIV diagnosis, 25% of users indicated recent multipartner chemsex, vs 28% of PrEP users and 5% of other MSM. Adjusting for age, ethnicity, UK birth, cis-trans status, sexual identity, education, settlement size and relationship status, participation in recent multipartner chemsex versus no chemsex was associated with greater odds of recent syphilis, gonorrhoea and chlamydia diagnosis. aORs for recent syphilis, gonorrhoea and chlamydia diagnoses were 2.6 (95% CI 1.7 to 4.1), 3.9 (95% CI 2.6 to 5.8) and 2.9 (95% CI 1.9 to 4.3), respectively, in HIV-diagnosed MSM; 1.9 (95% CI 1.1 to 3.3), 2.9 (95% CI 2.0 to 4.2) and 1.9 (95% CI 1.3 to 2.8), respectively, in PrEP users; and 4.0 (95% CI 2.3 to 6.9), 2.7 (95% CI 1.9 to 3.8) and 2.3 (95% CI 1.6 to 3.4), respectively, in other MSM. Conversely, exclusively dyadic chemsex had no significant associations with bacterial STI diagnoses among HIV-diagnosed MSM, only gonorrhoea (aOR 2.4, 95% CI 1.2 to 4.7) among PrEP users and syphilis (aOR 2.8, 95% CI 1.4 to 5.6) among other MSM.

DISCUSSION: Multipartner chemsex may drive the association between chemsex and bacterial STI diagnoses and thus should be the focus of future tailored chemsex interventions. Additionally, PrEP acceptability among MSM and particularly chemsex participants has generated an emergent group suitable for such interventions.

Original languageEnglish
Article numbersextrans-2020-054629
Pages (from-to)282-289
Number of pages8
JournalSexually Transmitted Infections
Volume97
Issue number4
Early online date15 Jan 2021
DOIs
Publication statusE-pub ahead of print - 15 Jan 2021

Bibliographical note

Funding Information:
The Department of Health and Social Care or PHE. EMIS-2017

Publisher Copyright:
© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.

Keywords

  • Sexual and Gender Minorities
  • Syphilis
  • Gonorrhoea/Gonorrhea
  • Chlamydia trachomatis,
  • HIV Infections
  • Men-who-have-sex-with-men
  • Chemsex
  • Pre-Exposure Prophylaxis
  • Illicit drugs
  • Substance-Related Disorders
  • Sexual Health

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