When to initiate highly active antiretroviral therapy in sub-Saharan Africa? A South African cost-effectiveness study

Abstract

Background: Large-scale programmes increasing access to highly active antiretroviral therapy (HAART) are being implemented in sub-Saharan Africa. However, cost-effectiveness of initiating treatment at different CD4 count thresholds has not been explored in resource-poor settings.

Methods: A cost-effectiveness analysis was conducted from a public health perspective using primary treatment outcomes, healthcare utilisation and cost data (Jan 2004 local prices; US dollars 1=7.6 Rands) derived from the Cape Town AIDS Cohort. A Markov state-transition model was developed to estimate life-expectancy, lifetime costs, quality-adjusted life-years (QALYs), cost per life-year and QALY gained for initiating HAART at three CD4 cell count thresholds (<200/microl, 200-350/microl and >350/microl), including the no antiretroviral therapy (No-ART) alternative. Each treatment option was compared with the next most effective undominated option.

Results: Mean life-expectancy was 6.2, 18.8, 21.0 and 23.3 years; discounted (8%) QALYs were 3.1, 6.2, 6.7 and 7.4; and discounted lifetime costs were US dollars 5,250, US dollars 5,434, US dollars 5,740, US dollars 6,588 for No-ART, and therapy initiation at <200/microl, 200-350/microl and >350/microl scenarios respectively. Clinical benefits increased significantly with early therapy initiation. Initiating therapy at <200/microl had an incremental cost-effectiveness ratio (ICER) of US dollars 54 per QALY versus No-ART, 200-350/microl had an ICER of US dollars 616 versus therapy initiation at <200/microl, and >350/microl had an ICER of US dollars 1,137 versus therapy initiation at 200-350/microl. ICERs were sensitive to HAART cost.

Conclusions: HAART is reasonably cost-effective for HIV-infected patients in South Africa, and most effective if initiated when CD4 count >200/microl. Deferring treatment to <200/microl would reduce the aggregate cost of treatment, but this should be balanced against the significant clinical benefits associated with early therapy.