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Title
Factors associated to incident sexually transmitted infections (STI) among men who have sex with men (MSM) and transgender women (TGW) on oral PrEP in Latin America: the ImPrEP study
Presenter
Mayara Secco Torres Silva
Authors
M. Secco Torres Silva1, T. Silva Torres1, C. Coutinho1, R. Ismério Moreira1, I. Costa Leite2, M. Cunha2, P.H. Amparo Costa Leite2, C. F Cáceres3, K. A Konda3, J. V Guanira3, H. Vega-Ramírez4, H. Vermandere5, S. Bautista-Arredondo5, B. Hoagland1, S. Wagner Cardoso1, M. Benedetti1, M.C. Pimenta6, V. Gonçalves Veloso1, B. Grinsztejn1, ImPrEP Study Group
Institutions
1Instituto Nacional de Infectologia Evandro Chagas (Fiocruz), Rio de Janeiro, Brazil, 2Escola Nacional de Saúde Pública (Fiocruz), Rio de Janeiro, Brazil, 3Universidad Peruana Cayetano Heredia, Lima, Peru, 4Instituto Nacional de Psiquiatria Ramón de la Fuente Muñiz, Mexico City, Mexico, 5Instituto Nacional de Salud Pública (INSP), Cuernavaca, Mexico, 6Ministério da Saúde, Brasília, Brazil

BACKGROUND: Latin America holds a high burden of STI, disproportionally affecting MSM and TGW. Despite structural challenges to build a local response, regional expansion of PrEP programs would strengthen a combination prevention approach, including STI screening. We aim to identify factors associated to STI diagnosis after PrEP initiation during the ImPrEP study.
METHODS: ImPrEP was a prospective, single-arm, open-label study, enrolling 9,509 MSM/TGW from February 2018 to December 2020. Syphilis serology was collected quarterly, while rectal chlamydia and gonorrhea molecular detection was performed annually. Participants with no STI testing during follow-up were excluded. The Cox proportional hazard model was used to identify factors associated with first diagnosis of any STI (p-value<=0.05).
RESULTS: Of 7,624 participants [Brazil(n=3,478); Mexico(n=2,541); Peru(n=1605)], 2350(30.8%) had at least one STI during follow-up. Participants younger than 30 years, reporting prior post-exposure prophylaxis use, multiple sex partners (>=2), condomless receptive anal sex (both within 3 months prior to baseline), presenting adequate PrEP adherence (medication possession rate [MPR]>=0.6 within 3 months prior to STI diagnosis), and having any STI at baseline had higher odds of having an incident STI during follow-up. (Figure 1). No substantial behavior change was observed after PrEP initiation (Table 1). During follow-up, 28.5% (n=670/2,350) had recurrent STI.



Table 1. Behavioral characteristics of ImPrEP participants diagnosed with any STI (n=2,350)

At study entryAt the time of first STI diagnosis
Multiple sex partners in the last 3 months (>= 2)2,095 (89.15%)1,991 (84.7%)
Condomless receptive anal sex1,731 (73.7%)1,037 (44.1%)
Use of stimulant drugs502 (21.4%)409 (17.4%)

CONCLUSIONS: High rates of STI among PrEP users underscore a need for tailored interventions, especially among young MSM/TGW. Our results suggest that PrEP users with incident STI were already highly vulnerable at the study’s baseline, not configuring a risk compensation behavior after PrEP initiation. PrEP programs represent an unprecedented opportunity to expand STI screening, preventing further HIV and bacterial STI transmission. Our findings also contribute to identifying individuals who would benefit most from bacterial STI prophylaxis.

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