Article

The new role of antiretrovirals in combination HIV prevention

aDepartment of Infectious Disease Epidemiology, Imperial College London, UK bCollege of Nursing Global, New York University, New York, New York cO'Neill Institute for National and Global Health Law, Georgetown University, Washington, District of Columbia dGeorge W. Bush Institute, Dallas, Texas, USA eLondon School of Hygiene and Tropical Medicine, UK fBill and Melinda Gates Foundation, Seattle, Washington, USA.
AIDS (London, England) (Impact Factor: 5.55). 01/2013; 27(3):447-58. DOI: 10.1097/QAD.0b013e32835ca2dd
Source: PubMed

ABSTRACT

: Antiretroviral drugs can reduce HIV acquisition among uninfected individuals (as pre-exposure prophylaxis: PrEP) and reduce onward transmission among infected individuals (as antiretroviral treatment: ART). We estimate the potential impact and cost-effectiveness of antiretroviral-based HIV prevention strategies.
: We developed and analysed a mathematical model of a hyperendemic setting with relatively low levels of condom use. We estimated the prevention impact and cost of various PrEP interventions, assuming a fixed amount of spending on PrEP; investigated the optimal role of PrEP and earlier ART in terms of epidemiological impact and cost; and systematically explored the impact of earlier ART and PrEP, in combination with medical male circumcision services; on HIV transmission.
: A PrEP intervention is unlikely to generate a large reduction in HIV incidence, unless the cost is substantially reduced. In terms of infections averted and quality adjusted life years gained, at a population-level maximal cost-effectiveness is achieved by providing ART to more infected individuals earlier rather than providing PrEP to uninfected individuals. However, early ART alone cannot reduce HIV incidence to very low levels and PrEP can be used cost-effectively in addition to earlier ART to reduce incidence further. If implemented in combination and at ambitious coverage levels, medical male circumcision, earlier ART and PrEP could produce dramatic declines in HIV incidence, but not stop transmission completely.
: A combination prevention approach based on proven-efficacy interventions provides the best opportunity for achieving the much hoped for prevention advance and curbing the spread of HIV.

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Available from: Ramzi A Alsallaq, Oct 07, 2014
    • "The conventional modelling approach assumes uptake is uniform, that is, the same proportion of potential users will take up an intervention regardless of its characteristics such as efficacy or cost, and often apply a number of uptake assumptions. This assumption is currently the norm for economic evaluations in the HIV prevention field, with a given level of uptake assumed based on at best expert opinion or comparable products or services, but normally just assumed with no data to back up the assumption (Cremin et al., 2013;Dimitrov et al., 2011;Gomez et al., 2012;Gray et al., 2011;Terris-Prestholt et al., 2014;Verguet et al., 2013;Verguet and Walsh, 2010;Walensky et al., 2012;Williams et al., 2011). Cost-benefit analyses can incorporate user preferences to value non-market impacts (Fujiwara and Campbell, 2011); however, the use of stated preference methods to explore the dynamic effect of intervention characteristics on uptake, and therefore intervention impact and cost-effectiveness, is novel. "
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    ABSTRACT: Model-based economic evaluations of new interventions have shown that user behaviour (uptake) is a critical driver of overall impact achieved. However, early economic evaluations, prior to introduction, often rely on assumed levels of uptake based on expert opinion or uptake of similar interventions. In addition to the likely uncertainty surrounding these uptake assumptions, they also do not allow for uptake to be a function of product, intervention, or user characteristics. This letter proposes using uptake projections from discrete choice experiments (DCE) to better parameterize uptake and substitution in cost-effectiveness models. A simple impact model is developed and illustrated using an example from the HIV prevention field in South Africa. Comparison between the conventional approach and the DCE-based approach shows that, in our example, DCE-based impact predictions varied by up to 50% from conventional estimates and provided far more nuanced projections. In the absence of observed uptake data and to model the effect of variations in intervention characteristics, DCE-based uptake predictions are likely to greatly improve models parameterizing uptake solely based on expert opinion. This is particularly important for global and national level decision making around introducing new and probably more expensive interventions, particularly where resources are most constrained.
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    • "Beyrer (2012) observed that while the current scientific evidence supports that ART-based prevention is feasible, it is also expensive and therefore its widespread use will require reduction in drug costs in high income countries. Cremin et al. (2013), in recent mathematical modelling analysis, suggested that earlier ART treatment and use of PrEP had significant cost and reach limitations undermining their effectiveness, but used in combination with other interventions would be the most effective in achieving reductions in HIV. "

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