HIV treatment as prevention: modelling the cost of antiretroviral treatment--state of the art and future directions

Abstract

Policy discussions about the feasibility of massively scaling up antiretroviral therapy (ART) to reduce HIV transmission and incidence hinge on accurately projecting the cost of such scale-up in comparison to the benefits from reduced HIV incidence and mortality. We review the available literature on modelled estimates of the cost of providing ART to different populations around the world, and suggest alternative methods of characterising cost when modelling several decades into the future. In past economic analyses of ART provision, costs were often assumed to vary by disease stage and treatment regimen, but for treatment as prevention, in particular, most analyses assume a uniform cost per patient. This approach disregards variables that can affect unit cost, such as differences in factor prices (i.e., the prices of supplies and services) and the scale and scope of operations (i.e., the sizes and types of facilities providing ART). We discuss several of these variables, and then present a worked example of a flexible cost function used to determine the effect of scale on the cost of a proposed scale-up of treatment as prevention in South Africa. Adjusting previously estimated costs of universal testing and treatment in South Africa for diseconomies of small scale, i.e., more patients being treated in smaller facilities, adds 42% to the expected future cost of the intervention.

Figure 1. Annual per patient cost of ART provision in four different settings in South Africa.

Based on . *, difference from public hospital significant at p<0.05. GPs, general practitioners; PHC, primary health care clinic; USD, US dollars.

Figure 2. Annual per patient cost of ART provision per type of outcome in four different settings in South Africa.

Based on . GPs, general practitioners; PHC, primary health care clinic; USD, US dollars.

Figure 3. Size-rank distribution of ART facilities in 2010 and projected to future years in order to implement a universal test-and-treat strategy in South Africa.

Figure 4. Impact of scale elasticity on future cost of a universal test-and-treat strategy in South Africa.

UTT, universal testing and treatment.