Our comparative evaluation of the mortality and transmission benefits of scaling up HIV testing and treatment in sub-Saharan Africa provides several important insights. First, universal testing and early treatment alone have important health and epidemiologic benefits, but we estimate that they provide about half of the benefits of a comprehensive scale-up strategy that also includes improved linkage to care and prevention of loss to follow-up. Second, the mortality and transmission benefits of scaling up HIV testing and treatment have implications for population growth. Finally, we estimate that even under a strategy of Comprehensive HIV care it will take longer than a decade to substantially reduce the burden of South Africa’s widespread epidemic.
Our results support the notion that universal testing and treatment have significant mortality benefits in South Africa. Recent estimates from South Africa suggest that ART may prolong life expectancy of infected individuals by 12.5 years.28
We estimate that a Comprehensive HIV testing, treatment, and care strategy will increase the average life expectancy of the entire
population by 22 months compared to the Status Quo. Between 1990 and 2006, life expectancy in South Africa declined by about 12 years. Scaling up HIV testing and treatment may go a significant way towards reversing that trend.29
While a Comprehensive plan with perfect linkage and full retention in care is not realistic, it provides an important bound for the possible benefits.
However, over a decade, the benefits of universal testing and treatment alone are much lower than the benefits of universal testing and treatment with improved linkage to care and prevention of loss to follow-up. This underscores the role of increasing the number of people who initiate treatment early: each individual who starts treatment early decreases the number of downstream infections by more than one. Insights from mathematical epidemiology suggest that, in the absence of ART, each individual infected with HIV transmits the infection to more than one person, on average, over his or her lifetime. Thus, the benefits of long-term effective ART are multiplied, and so are the losses from having individuals forego ART because of poor linkage to care or loss to follow-up.
Despite all these benefits, we find that even under the Comprehensive strategy of HIV care, the burden of disease over the next decade is expected to remain substantial. Some researchers suggest that it would take as long as 50 years to reduce HIV prevalence in South Africa to below 1%.10
Our estimates, which include a detailed microsimulation of HIV disease and treatment, demographic changes, and multiple transmission risk factors, agree with these estimates: we show a nearly linear decrease in prevalence of 4.2% over a decade, suggesting that it would take more than four decades at the estimated rate of decline to decrease prevalence to around 1%.
Our estimates of benefits rely on several important assumptions. Most importantly, we assumed that HIV transmission risk is reduced for individuals on ART. While much evidence supports this phenomenon, it has not been verified in a major clinical trial to date.30–31
We made several assumptions about the benefits of treatment in South Africa which affect our estimates of the longevity benefits of ART, but do not change the comparative effectiveness of the strategies we examined. We also assumed no behavioral risk modification with decreasing disease burden: for example, as HIV mortality and prevalence drop, individuals may perceive the disease as less threatening and increase risk behaviors such as multiple concurrent partnerships.32
However, we had no basis for assuming the type or extent of behavior risk modification. Finally, we assumed that the fertility rate will remain stable (i.e., the number of children per woman will not change over the next decade). A decrease in the fertility rate may slow the decline in prevalence, as the growth in population size will slow down while the number of infected individuals may not change appreciably.
Our analysis uses a detailed epidemiologic simulation model to estimate the mortality and transmission benefits of HIV testing, treatment, and care in South Africa, and quantifies the comparative effectiveness of alternative strategies for universal testing and treatment. We find that scaling up all aspects of HIV care nearly doubles the benefits of universal testing and treatment alone. An economic and operational evaluation of these strategies would further help in clarifying priorities.