Pre-exposure prophylaxis and bacterial sexually transmitted infections (STIs) among gay and bisexual men.
Trevor A Hart, Syed W Noor, Graham W Berlin, Shayna Skakoon-Sparling, Farideh Tavangar, Darrell Tan, Gilles Lambert, Daniel Grace, Nathan John Lachowsky, Jody Jollimore, Jordan Sang, Abbie Parlette, Allan Lal, Herak Apelian, David Moore, Joseph Cox, Engage Study
Author Information
Trevor A Hart: Department of Psychology, Ryerson University, Toronto, Ontario, Canada trevor.hart@ryerson.ca. ORCID
Syed W Noor: Department of Psychology, Ryerson University, Toronto, Ontario, Canada.
Graham W Berlin: Department of Psychology, Ryerson University, Toronto, Ontario, Canada. ORCID
Shayna Skakoon-Sparling: Department of Psychology, Ryerson University, Toronto, Ontario, Canada.
Farideh Tavangar: Department of Psychology, Ryerson University, Toronto, Ontario, Canada.
Darrell Tan: Division of Infectious Diseases, St Michael's Hospital, Toronto, Ontario, Canada.
Gilles Lambert: Direction Régionale de Santé Publique, Centre intégré universitaire de santé et de services sociaux du Centre-Sud-de-l'Île-de-Montréal du Québec, Montreal, Quebec, Canada.
Daniel Grace: Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
Nathan John Lachowsky: School of Public Health and Social Policy, University of Victoria, Victoria, British Columbia, Canada. ORCID
Jody Jollimore: Community Based Research Centre, Vancouver, British Columbia, Canada.
Jordan Sang: Epidemiology and Population Health Program, British Columbia Centre for Excellence in HIV/AIDS, Vancouver, British Columbia, Canada.
Abbie Parlette: Department of Psychology, Ryerson University, Toronto, Ontario, Canada.
Allan Lal: Epidemiology and Population Health Program, British Columbia Centre for Excellence in HIV/AIDS, Vancouver, British Columbia, Canada.
Herak Apelian: Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, Canada.
David Moore: Epidemiology and Population Health Program, British Columbia Centre for Excellence in HIV/AIDS, Vancouver, British Columbia, Canada.
Joseph Cox: Department of Epidemiology, Biostatistics and Occupational Health, School of Population and Global Health, McGill University, Montreal, Quebec, Canada.
OBJECTIVES: While pre-exposure prophylaxis (PrEP) prevents HIV acquisition among gay, bisexual and other men who have sex with men (GBM), PrEP-using GBM may be more likely to engage in sexual behaviours associated with bacterial STIs. We examined associations between PrEP use, condomless anal sex (CAS), number of anal sex partners, oral sex and bacterial STI diagnoses among GBM living in Canada's three largest cities. METHODS: Among HIV-negative/unknown-status GBM in the baseline of the Engage cohort study, we fit a structural equation model of the associations between any PrEP use, sexual behaviours and bacterial STI diagnosis. We estimated direct and indirect paths between PrEP use and STI via CAS, number of anal sex partners and oral sex. RESULTS: The sample included 2007 HIV-negative/unknown status GBM in Montreal, Toronto and Vancouver. There was a significant direct association between PrEP use and current STI diagnosis (β=0.181; 95% CI: 0.112 to 0.247; p<0.001), CAS (β=0.275; 95% CI: 0.189 to 0.361; p<0.001) and number of anal sex partners (β=0.193; 95% CI: 0.161 to 0.225; p<0.001). In the mediated model, the direct association between PrEP use and STIs was non-significant. However, the indirect paths from PrEP to CAS to STIs (β=0.064; 95% CI: 0.025 to 0.120; p=0.008), and from PrEP to greater number of anal sex partners to CAS to STIs were significant (β=0.059; 95% CI: 0.024 to 0.108; p=0.007). CONCLUSIONS: Our study adds to the growing awareness that PrEP use among GBM may be associated with bacterial STIs because PrEP users have more anal sex partners and are more likely to engage in CAS. The results underscore the importance of providing effective STI counselling and regular testing to PrEP users, adapting PrEP care and related STI testing to individual needs, and the need for effective prevention strategies for bacterial STIs.
