The survival benefits of antiretroviral therapy in South Africa

Abstract

Background: We sought to quantify the survival benefits attributable to antiretroviral therapy (ART) in South Africa since 2004.

Methods: We used the Cost-Effectiveness of Preventing AIDS Complications-International model (CEPAC) to simulate 8 cohorts of human immunodeficiency virus (HIV)-infected patients initiating ART each year during 2004-2011. Model inputs included cohort-specific mean CD4(+) T-cell count at ART initiation (112-178 cells/µL), 24-week ART suppressive efficacy (78%), second-line ART availability (2.4% of ART recipients), and cohort-specific 36-month retention rate (55%-71%). CEPAC simulated survival twice for each cohort, once with and once without ART. The sum of the products of per capita survival differences and the total numbers of persons initiating ART for each cohort yielded the total survival benefits.

Results: Lifetime per capita survival benefits ranged from 9.3 to 10.2 life-years across the 8 cohorts. Total estimated population lifetime survival benefit for all persons starting ART during 2004-2011 was 21.7 million life-years, of which 2.8 million life-years (12.7%) had been realized by December 2012. By 2030, benefits reached 17.9 million life-years under current policies, 21.7 million life-years with universal second-line ART, 23.3 million life-years with increased linkage to care of eligible untreated patients, and 28.0 million life-years with both linkage to care and universal second-line ART.

Conclusions: We found dramatic past and potential future survival benefits attributable to ART, justifying international support of ART rollout in South Africa.

Keywords: HIV; South Africa; highly active antiretroviral therapy.

Figure 1.

Results of univariate sensitivity analyses. The analyses examined the impact of adjusting selected model parameter values (individual bar labels) on the basis of cumulative survival benefits attributable to antiretroviral therapy (ART) in South Africa, in life-years (horizontal axis). The ranges of input values for each parameter are indicated alongside the corresponding bar graph. Results were most sensitive to ART efficacy, ART program retention, and the numbers of persons initiating ART. Abbreviation: HIV, human immunodeficiency virus.

Figure 2.

Survival benefits in South Africa following implementation of expanded human immunodeficiency virus (HIV) treatment and linkage-to-care policies, 2004–2030. Projections assume an annual HIV-infected population size projected by the Actuarial Society of South Africa [38]. The projections are depicted as cumulative survival benefits in millions of life-years (vertical axis), as a function of calendar year (horizontal axis). The vertical line demarcates January 2014, the time at which increased linkage to care and treatment is assumed to begin. Base-case survival benefits reached 17.9 million life-years by December 2030 (solid gray line). Universal access to second-line antiretroviral therapy (ART) starting in January 2014 yielded 21.7 million life-years (dashed grey line). Linkage to care of 10% of eligible untreated HIV-infected patients each year yielded 23.3 million life-years by 2030 (solid black line). Finally, universal access to second-line ART coupled with expanded case detection yielded 28.0 million life-years by 2030 (dashed black line).

Figure 3.

Sensitivity analyses of survival benefit projections following expanded human immunodeficiency virus (HIV) treatment and linkage-to-care policies in South Africa. Survival benefits are reported in millions of life-years as of December 2030 (vertical axis). Sensitivity analyses examined alternative values for the annual proportion of untreated HIV-infected persons eligible for antiretroviral therapy (ART) who are linked to care each year as a result of expanded testing (horizontal axis). In a scenario of increased linkage to care only and base-case availability of second-line ART for no more than 2.4% of ART recipients at any given time, survival benefits as of 2030 reached 25.9 million life-years with 20% linkage to care and 29.4 million life-years with 84% linkage to care (solid line). In a scenario of universal access to second-line ART starting in 2014, survival benefits as of 2030 reached 31.2 million life-years with 20% linkage to care and 35.6 million life-years with 84% linkage to care (dashed line).