UCSF

Background - Pre-exposure prophylaxis (PrEP) provides protection against HIV transmission but not against other sexually transmitted infections (STIs), which disproportionally affect men who have sex with men (MSM).This dissertation examines the association of PrEP initiation with subsequent patterns of condom use and STIs in MSM. A cohort of 525 MSM, 18 years and older, who self-identified as either high or low risk for HIV acquisition was followed for 13 months after initiating PrEP at a sexual health clinic in San Francisco.

Dissertation Aims - 1) review the literature to examine if PrEP is associated with changes in risk behavior in MSM; 2) determine the reasons why MSM who self-identify as low risk for HIV request PrEP; and 3) determine how PrEP use affects condom use and STIs rates in MSM who self-identify as high risk for HIV.

Methods – A systematic literature review was completed. The cohort was followed over 13 months subsequent to initiating PrEP. Questionnaires were used to examine condom use and biological assays were used to measure the frequency and type of STIs. Frequencies and descriptive analyses were completed, and multilevel logistic regression modeling was used to predict associations of condom use and STIs before and after initiation of PrEP. Framework analysis was used to identify themes and to develop a descriptive understanding of why low-risk MSM initiated and remained on PrEP.

Findings - No conclusive evidence was found that PrEP use leads to increased sexual risk behaviors. Overall, condom use decrease peaked at ~ 6 months and returned to baseline rates at ~12 months. Disparities in condom use and STI rates were observed within sub-populations of MSM, and condom use was found to be influenced by perceived risk. In both the low- and high-risk cohorts, anal GC/CT and syphilis decreased and pharyngeal GC/CT either remained constant or increased. MSM do not use PrEP solely to replace condoms, rather PrEP provides, peace of mind, sexual pleasure and safety and security.

Conclusion - In order to improve sexual health for MSM PrEP, STI screening and condom use education should be tailored to meet differing needs of sub populations. Sexual health discussion should include education on substance use, transmission of pharyngeal GC/CT and how MSM perceive sexual risk. Further research is needed to assess when more intensive counselling regarding condom use would be beneficial, how MSM perceive sexual risk and ways to reduce pharyngeal infections.