Alternative antiretroviral monitoring strategies for HIV-infected patients in east Africa: opportunities to save more lives?

Abstract

Background: Updated World Health Organization guidelines have amplified debate about how resource constraints should impact monitoring strategies for HIV-infected persons on combination antiretroviral therapy (cART). We estimated the incremental benefit and cost effectiveness of alternative monitoring strategies for east Africans with known HIV infection.

Methods: Using a validated HIV computer simulation based on resource-limited data (USAID and AMPATH) and circumstances (east Africa), we compared alternative monitoring strategies for HIV-infected persons newly started on cART. We evaluated clinical, immunologic and virologic monitoring strategies, including combinations and conditional logic (e.g., only perform virologic testing if immunologic testing is positive). We calculated incremental cost-effectiveness ratios (ICER) in units of cost per quality-adjusted life year (QALY), using a societal perspective and a lifetime horizon. Costs were measured in 2008 US dollars, and costs and benefits were discounted at 3%. We compared the ICER of monitoring strategies with those of other resource-constrained decisions, in particular earlier cART initiation (at CD4 counts of 350 cells/mm3 rather than 200 cells/mm3).

Results: Monitoring strategies employing routine CD4 testing without virologic testing never maximized health benefits, regardless of budget or societal willingness to pay for additional health benefits. Monitoring strategies employing virologic testing conditional upon particular CD4 results delivered the most benefit at willingness-to-pay levels similar to the cost of earlier cART initiation (approximately $2600/QALY). Monitoring strategies employing routine virologic testing alone only maximized health benefits at willingness-to-pay levels (> $4400/QALY) that greatly exceeded the ICER of earlier cART initiation.

Conclusions: CD4 testing alone never maximized health benefits regardless of resource limitations. Programmes routinely performing virologic testing but deferring cART initiation may increase health benefits by reallocating monitoring resources towards earlier cART initiation.

Figure 1

Schematic of constructs in computer simulation.

Figure 2

Efficient frontier of HIV monitoring strategies assuming two cART regimens are available.

Figure 3

Efficient frontier of HIV monitoring strategies assuming three cART regimens are available.

Figure 4

Efficient frontier of HIV monitoring strategies assuming no fixed number of cART regimens available.

Figure 5

Comparison of alternative strategies for allocating expenditures for a hypothetical HIV patient in East Africa. This figure shows a comparison of monitoring strategies for a patient newly diagnosed with HIV with a CD4 count of 350 cells/mm³. The right pair of bars shows a strategy that relies on routine viral load monitoring, whereas the left set of bars shows a strategy that relies more on clinical monitoring, and reallocates the money saved on less laboratory monitoring to fund earlier initiation of ARV. Even though both strategies incur the same lifetime expenditures, the strategy that employs less laboratory monitoring to enable earlier ARV initiation increases life expectancy by 1.5 quality-adjusted life years.