The Cost and Cost-Effectiveness of Alternative Strategies to Expand Treatment to HIV-Positive South Africans
Background: The South African government is considering alternative policies for scaling up publicly funded antiretroviral treatment (ART) for HIV/AIDS. Policies under discussion differ from previous policy in two dimensions: eligibility criterion and recruitment strategy. A number of analyses have considered the cost, cost effectiveness and/ or cost benefit of alternative eligibility criteria and recruitment strategies for a number of low- and middle income countries, including South Africa, but the detail with which cost was treated in these studies does not mirror the detail of the epidemiological projections, with authors often assuming the cost per patient-year of treatment would remain constant over time despite increases in the size of the treatment cohort by several hundred percent. In particular, economies of scale and the cost of generating the additional demand necessary for the assumed increase in recruited patients have not yet been not taken into account.
Methods: Over a twenty-year projection horizon, 2014-2033, we compared the projected epidemiological consequences and facility-level costs of eleven policy scenarios to the “current guidelines, status quo” (CG.SQ) scenario described above. The eleven scenarios are combinations of four alternative eligibility criteria and two alternative recruitment strategies. Alternative eligibility strategies and their abbreviations are: A CD4 threshold of 500 or less (abbreviated as “500”), all HIV positive people (also called “universal test and treat” or “UTT”), HIV positive individuals with seronegative partners (called “discordant couples” or “DC”) and HIV positive women who are pregnant (called “pregnant women” or “PW”). For the CG, the 500 and the UTT criteria, we explored both a “status quo” and a more ambitious “uniform expansion” (UE) recruitment strategy, which assumes increased testing and immediate ART initiation amongst 80% of the (eligible) population. For the DC and PW eligibility strategies, we additionally modeled an intermediate recruitment strategy called “prioritized expansion” (PE), which covers 80% of the targeted sub-population, while the rest of the population would continue to access testing and care at the “status quo”.
Results: Under the current guidelines and trends in testing, linkage to care and losses to retention (CG.SQ), 2.4 million adults and 202,067 children are estimated to be on treatment by mid- 2016, and 3.4 million adults and 135,424 children by 2033. If the current guidelines were kept, but testing, linkage to care and retention were improved to 80% each (CG.UE), these numbers would increase to 3.7 million adults and 236,471 children in 2016, and 5.3 million adults and 103,789 children in 2033. Under all other uniform expansion (UE) scenarios, there are more patients expected to be on treatment by mid-2016, and less by mid-2033, than under CG.UE; there is in fact an inverse relationship between the number of patients on treatment by mid-2016 and those on treatment by mid-2033 for all scenarios. This pattern of higher enrollment in early years followed by fewer patients in later years is a consequence of the epidemiological model’s assumption that people on treatment are less likely to transmit HIV infection.
Conclusions: We combined the outputs of an epidemiological and a cost model of the HIV epidemic in South Africa to calculate the incremental cost effectiveness of a range of strategies to expand eligibility beyond current guidelines. Previous research with EMOD-HIV has shown that more vigorous recruitment of patients with CD4 counts less than 350 appears to be an advantageous policy over a five-year horizon. Over 20 years, however, the model assumption that a person on treatment is 92% less infectious improves the cost-effectiveness of higher eligibility thresholds over more vigorous recruitment at the lower threshold of 350, averting HIV infections for between $1,700 and $2,800 (under our central assumptions), while more vigorous expansion under the current guidelines would cost more than $7,500 per incremental HIV infection averted.