Development of a Predictive Model for Sexually Transmitted Infections in Individuals Using Pre-Exposure Prophylaxis for HIV in Spain

Development of a Predictive Model for Sexually Transmitted Infections in Individuals Using Pre-Exposure Prophylaxis for HIV in Spain

Objective: To develop and validate a predictive model for acquiring sexually transmitted infections (STIs) in individuals using HIV pre-exposure prophylaxis (PrEP) within the national program providing this strategy.

Methods: Ambispective cohort study, multicentric (23 Spanish hospitals). All PrEP users, with follow-up within the program, will be included. Entry into the program will be considered as the baseline visit. From there, patients are followed quarterly, following the national protocols for monitoring PrEP users in Spain. At each visit, diagnosis of different STIs (serum, pharyngeal swab, urethral or urine sample, rectal swab, endocervical/vaginal swab, ulcer) is performed. Primary outcome variable: development of an STI (Yes/No). The following STIs will be considered: syphilis, Neisseria gonorrhoeae (NG) infection, Chlamydia trachomatis (CT) infection, lymphogranuloma venereum (LGV), Mycoplasma genitalium (MG) infection, genital herpes, hepatitis A, hepatitis B, hepatitis C, HIV infection, and MPOX. Secondary outcome variable: number of diagnosed STIs. In order to determine factors associated with acquiring an STI, multivariate analyses will be conducted using logistic regression. The best models will be analyzed in the validation population. To compare the models, we will follow the Bayesian approach suggested by Benavoli et al.

Inclusion Criteria:

• All individuals with documented initiation of oral PrEP (daily or event-driven regimens), who have collected the medication at least once and have taken at least one pill, will be included in the study.

The approved criteria for the use of oral PrEP in Spain, as recommended by the Spanish Gesida guidelines (GeSIDA. Recomendaciones sobre la Profilaxis Pre-Exposición para la Prevención de la Infección por VIH en España. Marzo 2023. Available at http://.gesida-seimc.org/category/guias-clinicas/otras-guias-vigentes/), are as follows:

• People without HIV infection at the time of cohort inclusion
• Age ≥ 16 yr who meet the following criteria:
• MSM and transgender women with at least two of the following criteria during the last year: > 10 sexual partners; Condomless anal sex; Chemsex; PEP; ≥ 1 STI
• Sex worker women who report non-habitual use of condoms.
• Cisgender males/females, who report condomless and present at least two of the same criteria as MSM and transgender.
• PWID with unsafe injection practices

Exclusion Criteria: none

-