The roll-out of antiretroviral therapy (ART) in South Africa has achieved “astounding” results, a mathematical model published in the online edition of the Journal of Infectious Diseases shows. Each person who started HIV therapy between 2004 and 2011 had an individual gain in life expectancy of 11 to 13 years. The estimated population lifetime survival benefit for all people initiating ART in this period was 21.7 million life-years. Increasing the number of people linked to care and expanded access to second-line therapies could increase the gain to 36 million life-years.
“This study contributes to a growing literature establishing the profound survival benefits resulting from investments in the global response to the HIV pandemic,” write the authors.
In an editorial accompanying the study, Sten H Vermund of the Institute for Global Health at Vanderbilt University said: “The magnitude of the benefit of South African ART-based programs is astounding.”
There are an estimated 5.6 million people living with HIV in South Africa, more than in any other country. Approximately 2.8 million people qualify for ART. However, despite the roll-out of treatment, a third of people eligible for therapy are not receiving treatment.
An international team of investigators wanted to quantify the cumulative survival benefit attributable to ART since its introduction in South Africa in 2004.
They used the Cost-Effectiveness of Preventing AIDS Complications-International model of HIV disease and treatment (CEPAC) to simulate and model the impact of ART roll-out in people starting ART between 2004 and 2011.
The simulation was based on data collected by the South African Catholic Bishops Conference, and estimated that patients had a mean age of 37 years and 33% were men. It was also estimated that mean CD4 cell count at the time of ART initiation ranged between 112 and 178 cells/mm3 and 46% of patients had a baseline viral load above 100,000 copies/ml. ART was assumed to achieve a reduction in AIDS-related mortality of between 56 and 96%. An estimated 78% of patients were assumed to have an undetectable viral load six months after initiating ART and the CD4 cell gain from baseline at this time was 148 cells/mm3. The modelled scenario also assumed that only 2.4% of patients had access to second-line ART and that the rate of retention in care at month 36 was between 55 and 71%. Additional data were also entered into the model to simulate the impact of ART should access to treatment and linkage to care improve.
The model was used to simulate survival for the cohort twice – first assuming no ART and then with ART.
The number of patients initiating ART each year grew from 50,000 in 2004 to 557,000 in 2011. By 2011, a total of 2,222,700 individuals had started HIV therapy.
Without ART, people had an estimated individual life expectancy of approximately two years. This increased to approximately 11 to 13 years with ART.
Overall, a total of 17.9 life-years would be saved with current ART policies, increasing to 21.7 million life-years with universal second-line ART, 23.3 million life-years with increased linkage to care for eligible but untreated patients and 28 million life-years with both improved linkage to care and universal second-line therapy. The most optimistic scenario involved a survival benefit of approximately 36 million life-years.
“We provided a model-based estimate of the survival benefits attributable to ART in South Africa,” write the authors. “In the base case, 21.7 million life-years were attributable to ART over the lifetime of all persons initiating ART during 2004-11, of which only 2.8 million life-years (12.7%) has been realized as of December 2012. Implementation of expanded testing and treatment policies…were projected to significantly increase these benefits.”
The author of the editorial stresses the investigators’ model was based on “data-driven assumptions with robust simulations…the assumptions were based on real-world programmatic information, not theoretical benefits of more-idealized programs.”
April MD et al. The survival benefits of antiretroviral therapy in South Africa. J Infect Dis, online edition, DOI: 10.1093/infdis/jit584, 2013.
Vermund SH Massive benefits of antiretroviral therapy in Africa. J Infect Dis, online edition, DOI: 10.1093/infdis/jit586, 2013.