Abstract and Introduction
The primary prevention of HIV infection remains a crucial priority; with 2.7 million new HIV infections world wide in 2008, the rate of new infections continues to outpace the rate at which HIV-positive individuals enter treatment. In recent years, HIV prevention research has focused on a variety of new biomedical strategies for preventing infection, such as male circumcision, vaccines, topical microbicides, and pre-exposure prophylaxis (PrEP) using antiretroviral (ARV) drugs.
PrEP entails providing HIV-negative individuals with ARV drugs, and it is widely anticipated as one of the most promising new prevention strategies. The PrEP drugs that have been studied to date (ie, tenofovir and emtricitabine) have an established safety profile in HIV-infected individuals, and ongoing trials of oral and topical PrEP among HIV-negative participants are grounded in animal studies,[3–7] phase I and II trial data in humans,[8,9] and initial data that did not demonstrate increased sexual risk behaviors among early PrEP trial participants. Simulation studies have modeled the effects of PrEP among populations in the United States, Africa, and India, forecasting the possibility of substantial reductions in HIV incidence.[11–14] Surveys, qualitative data, and anecdotal reports from the United States also indicate that some at-risk individuals have already used ARV drugs for HIV prophylaxis, suggesting that this strategy may be acceptable to some target users.[15–21]
Despite these indications of promise, many have noted that the practical implementation of PrEP is likely to meet stumbling blocks.[22–27] Although PrEP is a pharmaceutical intervention for preventing infection, using PrEP as a population-level HIV prevention strategy will require a broader conceptualization of this intervention. Mathematical models predicting PrEP’s effects suggest that depending on the efficacy of PrEP drugs, PrEP could provide meaningful benefits at the population level; however, PrEP’s population-level effectiveness may be offset by low uptake, suboptimal adherence to medications, and increases in HIV risk behavior among PrEP users (risk compensation).[11–14] To account for these possibilities, a broader conceptualization of PrEP should include not only PrEP drugs, but also nonpharmaceutical elements, including testing and assessment protocols, behavioral interventions, the long-term interactions between PrEP users and health care providers, and monitoring the population-level impacts of PrEP use.
The goal of this commentary is to aid ongoing efforts to plan for implementation in clinical practice by outlining an optimal PrEP implementation package. To maximize the impact of PrEP as an individual-level and population-level HIV prevention strategy, it will be necessary to bundle ARV prophylaxis drugs with a variety of nonpharmaceutical services. Continuing efforts to anticipate PrEP delivery in clinical practice should address demand for these services and the need for integrated care guidelines. This commentary first explains our focus on clinical practice as a venue for PrEP implementation, then offers a 5-part structure for PrEP implementation in clinical settings. This structure is based on a review and synthesis of the published literature related to PrEP, and it emphasizes aspects of PrEP that have previously received little attention. We conclude by enumerating several implications of viewing PrEP as an multicomponent prevention strategy.
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