Gay, bisexual and other men who have sex with men (herein, MSM) account for over half of the roughly 2000-3000 new HIV infections that occur in Canada each year, and have a staggering 131-fold higher risk of HIV acquisition than other Canadian men. The bulk of infections occur among MSM in urban centres. PrEP is an effective, safe and highly acceptable HIV prevention option among MSM, and health systems urgently need to implement PrEP more broadly as part of combination HIV prevention nationwide.

However, two key challenges have hindered efforts to optimize the impact of this promising intervention. First, health systems lack a coordinated strategy for targeting PrEP to those MSM at greatest HIV risk. Evidence-based criteria for identifying high-risk MSM for PrEP exist, including the presence of rectal bacterial sexually transmitted infections (STIs) or syphilis, and scoring ≥25 on the HIV Incidence Risk Index for MSM (HIRI-MSM), a validated risk index. Notably, the criteria are based on indicators that are routinely available to public health systems, such that ‘targeting’ can readily build on existing healthcare encounters. Measuring the success of such strategies in linking PrEP to those at highest risk is critical to optimizing scale-up.

Second, jurisdictions need more integrated systems for delivering PrEP at scale. At present, many patients struggle to get referred to a provider, because PrEP delivery relies too heavily on HIV specialists. Pilot projects aimed at decentralizing PrEP delivery in different ways are already underway in parts of Canada, including delivery by primary care providers (PCPs) and sexual health clinic nurses as studied by our team in a CIHR Implementation Science Component 1 grant in Toronto, and specialized PrEP clinics pioneered by team members in Vancouver and Hamilton. Comparative data are needed to understand which delivery strategies are most successful at retaining PrEP patients in care.

Together, these strategies for targeting and delivering PrEP define a cascade of steps, analogous to the HIV treatment cascade, that is key to tracking how those at high HIV risk are identified through routine healthcare encounters, linked to PrEP services, and ultimately initiated and retained on PrEP over time. The value of a cascade approach is that it articulates the specific steps involved in service delivery, and potential reasons for success or failure at each step. We will study the scale-up of these strategies using an implementation science framework. While access to PrEP medication is a key determinant of uptake due to cost, access is improving rapidly in Canada, and our research questions remain highly relevant to support the continued rise in PrEP use.

This project was made possible through a grant from CIHR.