However, as this study does not present costs per HIA it was not presented in the results section.
Preventing HIV/AIDS in young people
It is not unexpected that no studies of CE on microbicides have been published in the last four years, given the mostly disappointing news from the clinical trials [ 56 , 57 , 58 ]. Similarly, progress on a vaccine for HIV has been slow [ 59 ]. An international vaccine trial was discontinued in its second phase after interim analysis showed that the vaccine efficacy could not be obtained [ 60 , 61 ] and that it may actually make the subjects more susceptible to HIV [ 62 , 63 ].
So far, the only vaccine candidate to complete a phase III efficacy trial had no protective effect [ 64 ]. Furthermore, experimental and policy challenges to the development of a vaccine [ 65 ] make the hope more uncertain [ 63 ]. Modeling estimates suggest that even a modestly efficacious vaccine could have a substantial impact on controlling the epidemic and substantial financial savings; thus, the reason to continue investing resources on developing an effective vaccine [ 68 ]. Furthermore, other analysis on vaccines by Berndt and colleagues [ 69 ] highlight the key role played by product pricing, uptake rates, and efficacy in the CE analysis process.
In particular, they emphasize that CE estimates are sensitive to market prices; but, in turn, market prices are sensitive to volume discounts which can be achieved with more cost effective interventions. The authors also find that duration of protection would have a strong effect on the CE of a vaccine. Only one study [ 24 ] explicitly modeled the interaction between ART and prevention, although some effectiveness evidence does exist [ 70 , 71 , 72 , 73 ].
ART reduces viral load, but it also increases physical wellbeing, and patients' ability to engage in sexual activity. Hence, the interactions between providing ART and continuing prevention efforts should be further explored in terms of CE. However, another RCT in Rakai Uganda showed contradictory results [ 77 ] and other studies have not replicated the Mwanza level of efficacy [ 78 , 79 , 80 , 81 ]. Prevention of STIs follows in general the same recommendations as HIV prevention: reduction of number of sexual partners, condom use, etc. While some of the studies reviewed here suggest that treating STIs can be cost-effective, the epidemiological debate continues about the effectiveness of treating STIs as a way to prevent incident cases of HIV.
- HIV prevention cost-effectiveness: a systematic review!
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The controversy, over whether treating STIs has any impact on HIV, casts doubt on the CE results reviewed here, or at least provides further sources of uncertainty around them. Until the issue is settled, one alternative for researchers may be simply to limit the analysis to costs per STI treated. STI prevention and treatment interventions can be beneficial and cost effective in their own right. Among the biomedical interventions, male circumcision stands out as highly cost-effective for the level of efficacy demonstrated in the three RCTs.
The five CE studies [ 33 , 34 , 35 , 36 , 37 ] conducted in high-level generalized epidemics show that investment in this intervention can result in averting significantly large numbers of new HIV infections. However, for concentrated epidemics, studies are needed on the effectiveness of MC among men who have sex with men and on the CE among infants and among heterosexual adults.
Structural interventions include policy tools such as changing the tax structure, sex industry regulation, property rights and access to credit for women. Many of these programs have been evaluated recently, but they have not directly addressed HIV prevention, even though they may have had the potential to do so. For example, Cohen and Dupas [ 84 ] present results from Kenya where in-kind incentives and price subsidies were used for malaria prevention.
Women were randomized to free or three intervention price-levels of insecticide-treated bed nets if they attended a health post where general health and HIV prevention information was provided. They showed that higher incentives lower prices directly increased the uptake of bed nets.
HIV prevention cost-effectiveness: a systematic review | SpringerLink
Furthermore, HIV-positive individuals who learn their infection status are three times more likely to purchase condoms. However, the number of condoms purchased was small, only two on average. Testing alone does not seem to be as cost effective as other interventions [ 85 ]. Although few structural interventions measure HIV infections averted HIA , the main outcome of interest, structural interventions in general and conditional cash transfers [ 86 ] in particular could have a great potential to alter behaviors and prevent HIV.
Randomized controlled trials are needed to test various hypotheses regarding the optimal level of incentives, the best implementation strategies, and the best conditions for testing and treatment services. Structural and environmental interventions seem to have the potential to improve the effectiveness and CE of currently proven and new interventions.
More experimental and modeling evidence is needed to further explore the effects of changes in laws, taxes, and economic incentives on HIV prevention. Prospective trials need to be designed carefully, measuring potential benefits as well as the possibility of unintended harm, e. Also, a great challenge in conditional cash transfer CCT programs is the supply side quality of services ; this is particularly important for populations such as MSM who often do not use public services because of the discrimination they encounter.
Interventions in the context of programs are usually bundled; for example VCT and condom promotion may be provided at the same time. This not only makes it more difficult to evaluate the impact of a single intervention, it suggests that effectiveness is dependent not only on how an intervention is implemented, but also on what other interventions are bundled with it [ 3 , 87 ]. Better evaluation designs including multiple-arm controlled trials may be required so that each component, their synergies, as well as total effects, can be estimated.
Only when information is available about the likely synergies between different prevention interventions will CEA realize its potential in helping to identify the optimal package or the "right mix" for a given country or situation. The synergies between prevention and treatment can also be analyzed using a CE approach. At a basic level, it is clear that if prevention is enhanced, there will be less treatment needed in the future.
As treatment efforts become more widespread, prevention among HIV positive individuals is essential to reduce HIV transmission. As noted already, we did not find any CE studies on prevention for or with positives. The typology needs to be updated also: can prevention for people with HIV be similar, or are there prevention interventions that are specific and different for the positive population? In general, we have little empirical information about the interactions between different prevention and treatment strategies [ 88 ].
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- Preventing HIV/AIDS in young people: a systematic review of the evidence from developing countries.
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- Preventing HIV/AIDS in young people: a systematic review of the evidence from developing countries.
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More research is needed in the area of prevention for positives. Many unknowns remain in the relationship between scale and costs [ 89 ]. Particularly, in high-level generalized epidemic settings, there is still no clear CE evidence on how to achieve a scale sufficiently large to have a major impact on HIV incidence.
For example, male condoms continue to be one of the most widely used interventions, yet there is no recent CE evidence on how to achieve higher rates of condom utilization.
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Unit costs can decrease considerably with scale across many programs in different settings, but there can be important differences within the same country [ 90 ]. Also, non-linear relationships between unit costs and scale can occur [ 91 ]. The shape of the cost function [ 92 ] can reveal very different unit costs, and thus very different CE, at different scales of implementation.
These effects are almost universally ignored in the studies reviewed here and for the DCPP [ 3 , 89 ]. Non-linear effectiveness with scale is also an under-explored area, touched upon just by some of the MC studies reviewed here. Modeling work by Martina Morris and others [ 93 ] suggests that the relationship between behavior change and epidemic behavior can be far less linear than typically assumed in most CE models. For some basic interventions such as male condoms , there are estimates of the threshold at which the reproductive rate R 0 for the epidemic i.
R 0 may be useful as a theoretical outcome measure [ 95 ]. To estimate it empirically would require precise knowledge of how HIV is transmitted in each setting, and detailed information on sexual behaviors and networks. The specific effects of condom use on the dynamics of the epidemic are likely to be nonlinear. Similarly, the effects of ART on HIV transmission, due to its impact on longevity and sexual activity, are another example of nonlinear impacts which have been overlooked.
The literature continues to have only a few studies per type of intervention, not always with standardized and transparent methods, which does not facilitate comparison of results. Thus, the limited CE evidence is difficult to use in policy planning.
Few studies report how their results have been used in weighing policy alternatives. Moreover, the studies do not generally discuss how to interpret results in terms of thresholds, nor do they explore budgetary constraints and acceptability curves that would provide useful information to policymakers.
Modeling techniques to assess the CE of one or more interventions continue to be widely used. Models are a useful resource to estimate final outcomes when data are not available. However, modeling on untested assumptions can be a disservice for policy because it may raise false expectations of programs, as there are still many empty cells in the effectiveness matrices [ 96 ]; thus, many CEA studies can be highly speculative. More efforts should be made to compare models and develop international guidelines to provide readers with tools to evaluate the results and assumptions of a model.
Additional challenges are to have the guidelines followed, and finding the right tools to translate results from complex models to decision-makers.https://flatzalilelo.tk
Effectiveness studies that fail to show effectiveness would have no reason to include a CE component because an intervention without demonstrable effectiveness would have an infinite cost per unit of benefit. Thus, some of the peer-based programs, school education studies, STI treatment or the comprehensive community-prevention trials that have failed to show benefit should be assigned an infinity cost per DALY estimate [ 3 ]. Nevertheless, some CEA studies continue to include an implicit cost per unit of benefit based on selective assumptions.
As a body of work, they provide important information by analyzing CE ratios which depend upon a variety of factors including epidemiological characteristics, population targeted, coverage, unit prices and the technical efficiency for implementation. Focusing on the interventions that are most likely to be cost effective could help countries move from small, isolated programs to large-scale, comprehensive prevention efforts.
Given the limited resources, as new and potential interventions are shown to be effective, they need to be fully analyzed in terms of their CE. This review shows that many HIV-prevention interventions are cost effective in absolute terms using costs per DALY averted , and also in country-specific relative terms measured as percentage of GDP per capita.
Nevertheless, a number of observations can be made about the state of the literature.