Expedited Partner Therapy and the HIV Prevention Cascade for MSM in Peru

Background and Objectives. Expedited Partner Therapy (EPT) provides a framework to integrate STI control with HIV prevention through the sexual networks of men who have sex with men (MSM). Partner notification, testing, and treatment are the critical first steps of an HIV prevention cascade that bridges partner notification with linkage to HIV prevention services and population-scale reductions in HIV/STI incidence. EPT has been shown effective in reducing risks for STI re-exposure among heterosexual men and women but remains controversial for use with MSM. Previous studies of EPT with heterosexual couples have demonstrated significant decreases in the risk of recurrence for gonorrhea (GC), chlamydia (CT) and other STIs. Objections to the use of EPT with MSM center on the prevalence of undiagnosed HIV and syphilis among their partners, and fears that providing access to antibiotics will discourage STI-exposed individuals from seeking additional treatment. However, the evidence-based foundation for these objections is limited. In our previous pilot study of EPT for MSM with GC/CT in Peru, the odds of partner notification were significantly greater in the EPT arm (85.2%) than in the standard counseling arm (61.8%; OR=3.56). Additional research is needed to explore the use of EPT in MSM partnerships and to develop alternative conceptual frameworks capable of understanding the complex associations between EPT, STI control, and HIV prevention in MSM sexual networks. We hypothesize that EPT will increase the frequency of partner notification, encourage partners to seek HIV/STI counseling and testing, and promote linkage to HIV prevention and treatment services.

Differences in partnership formations and network structures of MSM necessitate correspondingly specific approaches to partner management. Heterosexual networks in previous partner therapy trials included a high frequency of stable or monogamous partnerships where HIV/STI risk could be localized and confined. In one study, the mean number of sexual partners in 3 months reported by men and women with GC/CT was 1.5. In another, 96% of women with CT named <2 recent partners, and most reported one. In these partnership contexts, EPT offers a simple method to control cyclical STI transmission in 2-core or 3-core networks of stable, recurrent sexual contacts. In contrast, sexual partnerships between MSM in the U.S. and Latin America are often part of large networks characterized by a diverse, concurrent mix of stable, casual, and anonymous partners. In a 2014 survey, MSM in Peru reported an average of 4.2 partners in the previous 30 days. The open structure of these decentralized, k-core networks limits the effectiveness of patient-delivered partner therapy in controlling cyclical STI re-transmission between stable partners. Instead, the primary benefit of EPT in these open-circuit networks lies in the potential to target HIV/STI prevention technologies to the highest risk nodes of diffuse and diverse sexual networks.

EPT offers an intervention ideally suited to Peru's local epidemiologic context. The Peruvian HIV epidemic is concentrated in the population of MSM and transgender women (TW) and associated with STI co-infection. In high-risk MSM populations, partner- and network-level characteristics have been found to be important factors contributing to HIV/STI acquisition. Sexual networks of at-risk MSM are often composed of a concurrent mix of stable/primary, casual (recurrent or single contact), anonymous, and/or commercial partners, with varying degrees of communication, trust, and responsibility. Although stable partners are considered "low-risk" for exposure to HIV/STIs, the lack of objective information on HIV/STI status and the increased likelihood of condomless intercourse in these partnership contexts lead to a high frequency of HIV/STI transmission. Casual sexual partners are often maintained concurrent with primary partners or anonymous contacts and contribute to the dissemination of HIV/STIs across diffuse social and geographic boundaries. Anonymous partners, by definition untraceable, are common and present significant challenges for STI control.

Previous research has emphasized how interpersonal contexts influence partner management tools. Internet systems encourage notification in casual partnerships with minimal interpersonal commitment and low perceived risk of re-exposure, while efforts to target prevention outreach to the dates and times of anonymous contacts have shown success. In contrast, EPT is most effective in stable or recurrent casual partnerships where trust and communication are assumed and the potential for STI re-exposure is high. While any comprehensive partner management strategy will require an array of systems to address the range of partnerships structuring MSM networks, EPT provides a critical tool to address HIV/STI transmission networks.

To evaluate the potential effectiveness of EPT for use with MSM, the investigators have identified three key questions: