Background: HPTN 073 assessed the feasibility, acceptability, and safety of pre-exposure prophylaxis (PrEP) for Black men who have sex with men (BMSM). Understanding the relationship between PrEP uptake, and sexually transmitted infection (STI) acquisition is critical to informing best practices in PrEP delivery for BMSM, a population most highly affected by HIV in the US.
Methods: From August 2013 - September 2014, we enrolled 226 HIV-uninfected BMSM in three cities (Los Angeles, CA; Washington, DC; and Chapel Hill, NC). All participants received client-centered care coordination and were offered daily oral PrEP with emtricitabine/tenofovir. Men were followed for 12 months with scheduled clinical visits and STI testing (rectal and urine NAAT for gonorrhea and chlamydia, RPR for syphilis) at weeks 26 and 52. Logistic regression was used to examine the association between STI prevalence and baseline factors. Person-years (PY) follow-up time was calculated to the first STI event or last STI date from either the PrEP acceptance date or enrollment date depending if BMSM accepted PrEP.
Results: Baseline STI prevalence was 14%; no differences were noted among study sites. Men < 25 were more likely to have a baseline STI (25.3% vs. 6.7%; OR 4.39, 95% CI: 1.91, 10.11). Sixty participants (26.5%) acquired ≥1 STI during follow-up, 9 participants had an STI at both follow-up visits. Higher rates of STIs were seen during follow-up among those with STIs at baseline (Table 1). STI rate was 32.8/100 PY (24.3, 43.2) among those who accepted PrEP compared to those who declined 26.8/100 PY (12.9, 49.3).

Characteristics of Incident STIs by PrEP Acceptance and Visit
[Characteristics of Incident STIs by PrEP Acceptance and Visit]

Conclusions: While we found higher rates of STIs in younger BMSM, the overall rates of STI in this trial were lower than in prior PrEP trials with no increase over time. BMSM with STIs at PrEP initiation may require additional counseling on STI acquisition risk and more frequent STI testing during follow-up.