Integrated Female Sexually Transmitted Infection Testing for HIV Epidemic Control through PrEP: The IN-STEP study

PROJECT SUMMARY Globally, new female HIV infections are concentrated in women outside of known key populations. Identifying women at high risk for HIV acquisition and successfully engaging them in HIV prevention services, particularly pre-exposure prophylaxis (PrEP) programs, is an urgent priority for sustaining epidemic control, protecting U.S. investments and reducing the risk of future cross-border transmission. However, these tools have low to moderate sensitivity, missing many women at high risk for HIV. This is partly due to underreporting of risk factors, but also because many women are at heightened HIV risk solely through relationships with high-risk male partners. Moreover, many women enrolled into PrEP programs stop using PrEP within months of initiation. Decades of research shows that curable sexually transmitted infections (cSTI) are objective markers of future HIV risk, but cSTI testing largely has been omitted from HIV programs in high burden settings. With the advent of lower cost multiplex cSTI testing and point of care diagnostics, there is new opportunity to determine whether integrating female cSTI testing services into HIV programs can improve HIV epidemic control. Here, we propose an individually randomized effectiveness implementation trial of SRST plus cSTI diagnostic testing for chlamydia, gonorrhea, trichomonas, and syphilis compared to SRST alone to increase PrEP use among women aged 15-39 years. We hypothesize that cSTI testing will increase PrEP use primarily through (i) improved identification of women at high risk for HIV and (ii) enhancement of self-perceived HIV risk. The proposed research will be nested within the Rakai Community Cohort Study, a population-based HIV surveillance cohort. To support Aim 1, ~4,500 HIV-negative women will be individually randomized 1:1 to PrEP screening based on SRST plus cSTI diagnostic testing (intervention) versus PrEP screening based on SRST alone (control arm). Both arms will be offered syndromic case management for cSTIs and syphilis testing for pregnant women (standard of care). The primary outcomes will be PrEP uptake, adherence, and persistence, assessed through clinical records and drug level testing. To support Aim 2, we will perform a mixed-methods, implementation science evaluation using qualitative and quantitative methods to assess the mechanisms, barriers, and facilitators to improving PrEP outcomes through cSTI testing and how this varies by cSTI pathogen, SRST outcomes, and demographic profiles. To support Aim 3, we will use mathematical models to evaluate different cSTI testing approaches to reduce HIV incidence at a population level. We will also model broader health benefits of cSTI testing. Results will provide actionable, RCT-level, and population-level empirical evidence to inform the strategic delivery of high-impact HIV interventions, including U.S. developed innovations such as lenacapavir, not to mention strengthening U.S. leadership and investments in the prevention and treatment of HIV and other STIs.