Health systems and HIV treatment in sub-Saharan Africa: Matching intervention and program evaluation strategies

Objectives International donors financing the delivery of antiretroviral treatment (ART) in developing countries have recently emphasized their commitment to rigorous evaluation of ART impact on population health. In the same time frame but different contexts, they have announced that they will shift funding from vertically-structured (i.e., disease-specific) interventions to horizontally-structured interventions (i.e., staff, systems and infrastructure that can deliver care for many diseases). We analyze likely effects of the latter shift on the feasibility of impact evaluation. Methods We examine the effect of the shift in intervention strategy on (i) outcome measurement, (ii) cost measurement, (iii) study-design options, and the (iv) technical and (v) political feasibility of program evaluation. Results As intervention structure changes from vertical to horizontal, outcome and cost measurement are likely to become more difficult (because the number of relevant outcomes and costs increases and the sources holding data on these measures become more diverse); study design options become more limited (because it is often impossible to identify a rigorously defined counterfactual in horizontal interventions); the technical feasibility of interventions is reduced (because lag times between intervention and impact increase in length and effect mediating and modifying factors increase in number); and political feasibility of evaluation is decreased (because national policymakers may be reluctant to support the evaluation). Conclusions In the choice of intervention strategy, policymakers need to consider the effect of intervention strategy on impact evaluation. Methodological studies are needed to identify the best approaches to evaluate the population health impact of horizontal interventions.Impact evaluation, health systems, HIV, antiretroviral treatment, Africa

Estimating health worker need to provide antiretroviral treatment in the developing world

Despite recent international efforts to increase antiretroviral treatment (ART) coverage, more than 5 million people who need ART in developing countries do not receive such treatment. Shortages of human resources to treat HIV/AIDS (referred to herein as HRHA) are one of the main constraints to further scaling up ART. Planning expansion of ART depends on the ability to predict how many HRHA will be needed in the future. We investigate whether taking into account positive feedback from the current supply of HRHA to future HRHA need substantially alters predictions. This feedback occurs because an increase in the number of HRHA implies an increase in the number of individuals receiving ART and – because ART is a lifelong treatment and is effective in prolonging the lives of HIV-positive people – a rise over time in the number of people requiring ART.Disease, control, global health, HIV/AIDS, Africa.

A Mathematical Model for Estimating the Number of Health Workers Required for Universal Antiretroviral Treatment

Despite recent international efforts to increase antiretroviral treatment (ART) coverage, it is estimated that more than 5 million people who need ART in developing countries do not receive such treatment. Shortages of human resources to treat HIV/AIDS (HRHA) are one of the main constraints to scaling up ART. We develop a discrete-time Markovian model to project the numbers of HRHA required to achieve universal ART coverage, taking into account the positive feedback from HRHA numbers to future HRHA need. Feedback occurs because ART is effective in prolonging the lives of HIVpositive people who need treatment, so that an increase in the number of people receiving treatment leads to an increase in the number of people needing it in future periods. We investigate the steady-state behavior of our model and apply it to different regions in the developing world. We find that taking into account the feedback from the current supply of HRHA to the future HRHA need substantially increases the projected numbers of HRHA required to achieve universal ART coverage. We discuss the policy implications of our model.Mathematical model, health workers, universal antiretroviral treatment

Medicine and Economics: Accounting for the full benefits of childhood vaccination in South Africa

While remarkable gains in health have been achieved since the mid-20th century, these have been unequally distributed, and mortality and morbidity burdens in some regions remain enormous. Of the almost 10 million children under 5 years of age who died in 2006, only 100 000 died in industrialised countries, while 4.8 million died in sub-Saharan Africa.1 In deciding whether to finance an intervention, policy makers commonly weigh the expected population health gains against its costs. Most vaccinations included in national immunisation schedules are inexpensive2 and health gains to costs are very favourable compared with other health interventions. Newer vaccinations, such as those with pneumococcal conjugate vaccine (PCV) or rotavirus vaccine, are also effective in averting child mortality and morbidity but are expensive relative to those commonly included in national immunisation schedules. Policy makers may therefore decide that – at current prices – the comparison of health gains with costs does not justify the free public provision of these vaccinations. The authors of this paper argue that in addition to the health benefits of vaccinations, their effects on education and income3 and benefits for unvaccinated community members are considerable and should be included in calculations to establish their value.Disease, control, global health, vaccination, HIV/AIDS, Africa.

An approach to solving constraint satisfaction problems using asynchronous teams of autonomous agents

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1994.Includes bibliographical references (leaves 145-147).by Salal Humair.M.S

A Mathematical Model for Estimating the Number of Health Workers Required for Universal Antiretroviral Treatment

Despite recent international efforts to increase antiretroviral treatment (ART) coverage, it is estimated that more than 5 million people who need ART in developing countries do not receive such treatment. Shortages of human resources to treat HIV/AIDS (HRHA) are one of the main constraints to scaling up ART. We develop a discrete-time Markovian model to project the numbers of HRHA required to achieve universal ART coverage, taking into account the positive feedback from HRHA numbers to future HRHA need. Feedback occurs because ART is effective in prolonging the lives of HIV-positive people who need treatment, so that an increase in the number of people receiving treatment leads to an increase in the number of people needing it in future periods. We investigate the steady-state behavior of our model and apply it to different regions in the developing world. We find that taking into account the feedback from the current supply of HRHA to the future HRHA need substantially increases the projected numbers of HRHA required to achieve universal ART coverage. We discuss the policy implications of our model.

HIV Treatment as Prevention: Systematic Comparison of Mathematical Models of the Potential Impact of Antiretroviral Therapy on HIV Incidence in South Africa

Background: Many mathematical models have investigated the impact of expanding access to antiretroviral therapy (ART) on new HIV infections. Comparing results and conclusions across models is challenging because models have addressed slightly different questions and have reported different outcome metrics. This study compares the predictions of several mathematical models simulating the same ART intervention programmes to determine the extent to which models agree about the epidemiological impact of expanded ART. Methods and Findings: Twelve independent mathematical models evaluated a set of standardised ART intervention scenarios in South Africa and reported a common set of outputs. Intervention scenarios systematically varied the CD4 count threshold for treatment eligibility, access to treatment, and programme retention. For a scenario in which 80% of HIV-infected individuals start treatment on average 1 y after their CD4 count drops below 350 cells/µl and 85% remain on treatment after 3 y, the models projected that HIV incidence would be 35% to 54% lower 8 y after the introduction of ART, compared to a counterfactual scenario in which there is no ART. More variation existed in the estimated long-term (38 y) reductions in incidence. The impact of optimistic interventions including immediate ART initiation varied widely across models, maintaining substantial uncertainty about the theoretical prospect for elimination of HIV from the population using ART alone over the next four decades. The number of person-years of ART per infection averted over 8 y ranged between 5.8 and 18.7. Considering the actual scale-up of ART in South Africa, seven models estimated that current HIV incidence is 17% to 32% lower than it would have been in the absence of ART. Differences between model assumptions about CD4 decline and HIV transmissibility over the course of infection explained only a modest amount of the variation in model results. Conclusions: Mathematical models evaluating the impact of ART vary substantially in structure, complexity, and parameter choices, but all suggest that ART, at high levels of access and with high adherence, has the potential to substantially reduce new HIV infections. There was broad agreement regarding the short-term epidemiologic impact of ambitious treatment scale-up, but more variation in longer term projections and in the efficiency with which treatment can reduce new infections. Differences between model predictions could not be explained by differences in model structure or parameterization that were hypothesized to affect intervention impact

Health benefi ts, costs, and cost-eff ectiveness of earlier eligibility for adult antiretroviral therapy and expanded treatment coverage: a combined analysis of 12 mathematical models

Background New WHO guidelines recommend initiation of antiretroviral therapy for HIV-positive adults with CD4 counts of 500 cells per μL or less, a higher threshold than was previously recommended. Country decision makers have to decide whether to further expand eligibility for antiretroviral therapy accordingly. We aimed to assess the potential health benefi ts, costs, and cost-eff ectiveness of various eligibility criteria for adult antiretroviral therapy and expanded treatment coverage. Methods We used several independent mathematical models in four settings—South Africa (generalised epidemic, moderate antiretroviral therapy coverage), Zambia (generalised epidemic, high antiretroviral therapy coverage), India (concentrated epidemic, moderate antiretroviral therapy coverage), and Vietnam (concentrated epidemic, low antiretroviral therapy coverage)—to assess the potential health benefi ts, costs, and cost-eff ectiveness of various eligibility criteria for adult antiretroviral therapy under scenarios of existing and expanded treatment coverage, with results projected over 20 years. Analyses assessed the extension of eligibility to include individuals with CD4 counts of 500 cells per μL or less, or all HIV-positive adults, compared with the previous (2010) recommendation of initiation with CD4 counts of 350 cells per μL or less. We assessed costs from a health-system perspective, and calculated the incremental cost (in US$) per disability-adjusted life-year (DALY) averted to compare competing strategies. Strategies were regarded very cost eff ective if the cost per DALY averted was less than the country’s 2012 per-head gross domestic product (GDP; South Africa:$8040; Zambia: $1425; India:$1489; Vietnam: $1407) and cost eff ective if the cost per DALY averted was less than three times the per-head GDP. Findings In South Africa, the cost per DALY averted of extending eligibility for antiretroviral therapy to adult patients with CD4 counts of 500 cells per μL or less ranged from$237 to $1691 per DALY averted compared with 2010 guidelines. In Zambia, expansion of eligibility to adults with a CD4 count threshold of 500 cells per μL ranged from improving health outcomes while reducing costs (ie, dominating the previous guidelines) to$749 per DALY averted. In both countries results were similar for expansion of eligibility to all HIV-positive adults, and when substantially expanded treatment coverage was assumed. Expansion of treatment coverage in the general population was also cost eff ective. In India, the cost for extending eligibility to all HIV-positive adults ranged from $131 to$241 per DALY averted, and in Vietnam extending eligibility to patients with CD4 counts of 500 cells per μL or less cost $290 per DALY averted. In concentrated epidemics, expanded access for key populations was also cost eff ective. Interpretation Our estimates suggest that earlier eligibility for antiretroviral therapy is very cost eff ective in lowincome and middle-income settings, although these estimates should be revisited when more data become available. Scaling up antiretroviral therapy through earlier eligibility and expanded coverage should be considered alongside other high-priority health interventions competing for health budgets

Health benefits, costs, and cost-effectiveness of earlier eligibility for adult antiretroviral therapy and expanded treatment coverage: a combined analysis of 12 mathematical models.

BACKGROUND: New WHO guidelines recommend ART initiation for HIV-positive persons with CD4 cell counts ≤500 cells/µL, a higher threshold than was previously recommended. Country decision makers must consider whether to further expand ART eligibility accordingly. METHODS: We used multiple independent mathematical models in four settings-South Africa, Zambia, India, and Vietnam-to evaluate the potential health impact, costs, and cost-effectiveness of different adult ART eligibility criteria under scenarios of current and expanded treatment coverage, with results projected over 20 years. Analyses considered extending eligibility to include individuals with CD4 ≤500 cells/µL or all HIV-positive adults, compared to the previous recommendation of initiation with CD4 ≤350 cells/µL. We assessed costs from a health system perspective, and calculated the incremental cost per DALY averted ($/DALY) to compare competing strategies. Strategies were considered 'very cost-effective' if the$/DALY was less than the country's per capita gross domestic product (GDP; South Africa: $8040, Zambia:$1425, India: $1489, Vietnam:$1407) and 'cost-effective' if $/DALY was less than three times per capita GDP. FINDINGS: In South Africa, the cost per DALY averted of extending ART eligibility to CD4 ≤500 cells/µL ranged from$237 to $1691/DALY compared to 2010 guidelines; in Zambia, expanded eligibility ranged from improving health outcomes while reducing costs (i.e. dominating current guidelines) to$749/DALY. Results were similar in scenarios with substantially expanded treatment access and for expanding eligibility to all HIV-positive adults. Expanding treatment coverage in the general population was therefore found to be cost-effective. In India, eligibility for all HIV-positive persons ranged from $131 to$241/DALY and in Vietnam eligibility for CD4 ≤500 cells/µL cost $290/DALY. In concentrated epidemics, expanded access among key populations was also cost-effective. INTERPRETATION: Earlier ART eligibility is estimated to be very cost-effective in low- and middle-income settings, although these questions should be revisited as further information becomes available. Scaling-up ART should be considered among other high-priority health interventions competing for health budgets. FUNDING: The Bill and Melinda Gates Foundation and World Health Organization