Preparing for the Future of HIV/AIDS in Africa A Shared Responsibility (2011) / Chapter Skim
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Appendix A: Projecting the Burden of HIV/AIDS
Appendix A: Projecting the Burden of HIV/AIDS
Pages 171-194
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From page 171... ...
. Over the longer term, less predictable factors could alter the risk of HIV infection and the resources available to combat the epidemic.
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From page 172... ...
Since the degree to which the two behavioral effects in Table A-1 will manifest as treatment access increases is still unknown and will likely be responsive to national HIV/AIDS policies, the baseline model ignores these and the other indirect effects of ART on HIV transmission.2 Others have made projections of the impact of particular interventions over 1 aids2031 is a consortium of partners who came together to look at what has been learned about the HIV/AIDS response and consider the implications of the changing world around the HIV/AIDS pandemic (aids2031 Consortium, 2010)
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From page 173... ...
.3 This counterintuitive assumption allows prevalence to saturate, but generates some odd properties since increased treatment decreases incidence through this mechanism in addition to the cal culated reduction in the transmission probability. Granich and colleagues also assume that diagnosis of HIV reduces risk behavior by 50 percent, a possibility supported only by studies of self-reported behavior change shortly after the start of treatment (Venkatesh et al., 2010)
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From page 174... ...
. Models of Johnson representing South Africa show that treatment improves survival and that prevention interventions can have an impact (Johnson, 2010)
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From page 175... ...
In African health care facilities that deliver publicly funded ART services, recruitment of a new patient entails an implicit commitment by the facility and its funders to continue to provide that treatment under the same financial arrange ments for the patient's lifetime. To meet this commitment to enrolled patients implies that, when resources are scarce, the facility must give priority to existing enrolled patients over patients who have not yet begun treatment.
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From page 176... ...
The slow response of the epidemic to even quite dramatic changes in either treatment or prevention policy is due to the long incubation period between HIV infection and the onset of symptoms (approximately 9 years from HIV acquisition to a CD4 count of 200, with variation depending on age, prior health condition, and other factors) (Aalen et al., 1997; Van Der Paal et al., 2007)
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From page 177... ...
. Mother-to-child, or perinatal, transmission continues to account for a sub stantial, although decreasing, portion of these new HIV infections in many African countries (UNAIDS and WHO, 2009)
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From page 178... ...
The effort is complicated by vertical transmission of HIV leading to higher-than-background mortality in some children and the influence of HIV infection on reducing fertility. The use of ART makes it more likely that children will be born to HIV-infected mothers and less likely that they will acquire HIV infection vertically.
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From page 179... ...
In the estimation of treatment costs for aids2031, the costs include the unit costs of antiretroviral drugs, estimated as $167.65 for first-line and $1016.48 for second-line drugs based on average costs in 2007. Added to these figures are laboratory costs of $190.94 per patient per year and service delivery costs of $72.05 per patient per year for Africa; the service delivery costs are assumed to be greater in other regions.
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From page 180... ...
However, when one looks at the data, PEPFAR expenditure per patient is substantially greater than would be expected from PEPFAR's own survey of facilities, suggesting that more than half of PEPFAR's AIDS treatment expendi tures are consumed before they reach the treatment site. Some of these additional costs above the facility level are justified as a contribution to the quality and efficiency of ART service delivery on the ground, while others are probably due to inadequate coordination, overly complex administrative procedures, and even fraud and abuse.
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From page 181... ...
However, counseling and testing done to identify patients who require treatment may be less elaborate and therefore less effective at reducing risk behavior compared with counseling and testing aimed primarily at HIV prevention.
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In this figure, current trends indicates that coverage of key interventions continues to expand to 2015 as it has in the past few years; rapid scale-up indicates that political will to achieve universal access is strong, and resource availability continues to grow rapidly; hard choices indicates that resources for HIV/AIDS programs are limited, so there is a focus on scaling up only the most cost-effective approaches for prevention; and structural change indicates a greater focus on structural change that can reduce vulnerability to HIV/AIDS and produce a more sustainable response (aids2031 Costs and Financing Working Group, 2010)
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From page 183... ...
It should be noted that treatment costs accumulate over time. Depending on policy choices currently available, the cumulated cost of HIV/AIDS treatment between 2010 and 2050 is likely to be between $200 billion and $800 billion (Figure A-4)
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From page 184... ...
NOTE: Using the committee model, a bivariate sensitivity analysis comparing the influ fig A-4.eps ence of two parameters was used to show trade-offs, holding constant a set of epidemio logical and cost assumptions as detailed in Annex A-1. SOURCE: Committee projections using data from UNAIDS 2008.
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From page 185... ...
Who is legally and practically able to prescribe and administer antiretroviral drugs will depend upon the organization of health care in a country and the legal constraints on health care workers. A cascade model of care whereby patients with greater complications can be referred to secondary and tertiary services as required appears to be ideal, with less specialized health care workers maintaining patients on ART.
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Sexually Transmitted Infections 82(Suppl.
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From page 187... ...
Sexually Transmitted Infections. Hecht, R., L
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1996. Human immunodeficiency virus infection and other sexually transmitted diseases in developing countries: Public health importance and priorities for resource allocation.
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2009. Male circumcision for HIV prevention in high HIV prevalence settings: What can mathematical modelling contribute to informed decision making?
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From page 190... ...
While real policy could follow either pattern, the partial adjustment approach better captures the policy reality of insufficient resources to enroll everyone who needs treatment by any given definition. Assuming a constant rate of people becoming newly in need of treatment, b, and the death rate of those in need, a, and those on treatment, μ, we can calculate the relationship between the fraction of those newly in need starting treatment immediately, φ; the rate of those in need starting treatment, γ ; and the patterns of treatment coverage and mortality.
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From page 191... ...
For given rates of HIV incidence and treatment initiation, an HIV epidemic will approach a long-run equilibrium coverage rate, which for high incidence and low treatment initiation will be substantially less than universal coverage.
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From page 192... ...
These models of Blower, Granich, Baggaley, Phillips, and Johnson have been used to explore a number of HIV/AIDS prevention interventions, including the impact of treatments for sexu ally transmitted infections (STIs) (Over and Piot, 1996; White et al., 2008)
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From page 193... ...
To reflect the very different prevalences across Africa, which presumably reflect the fraction of the population engaging in risk behaviors, country-specific fractions at risk, k, are estimated from a constant incidence rate: AI 0 + IR0 H 0 k= 69 IR0 P15 0 69 where H0 is the number HIV-infected, and P15 0 is the total population aged 15−64. IR0 is an external variable.
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From page 194... ...
; prevention interventions that reduce susceptibility to infection and risk behaviors; and the proportion of those infectious with a reduced viraemia due to treatment relative to the baseline proportion treated: Pr ev t τ t IRt = IR0 Pr ev 0τ o (1 – ct .m.ε )
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