The value of point-of-care CD4+ and laboratory viral load in tailoring antiretroviral therapy monitoring strategies to resource limitations

Abstract

Objective: To examine the clinical and economic value of point-of-care CD4 (POC-CD4) or viral load monitoring compared with current practices in Mozambique, a country representative of the diverse resource limitations encountered by HIV treatment programs in sub-Saharan Africa.

Design/methods: We use the Cost-Effectiveness of Preventing AIDS Complications-International model to examine the clinical impact, cost (2014 US$), and incremental cost-effectiveness ratio [$/year of life saved (YLS)] of ART monitoring strategies in Mozambique. We compare: monitoring for clinical disease progression [clinical ART monitoring strategy (CLIN)] vs. annual POC-CD4 in rural settings without laboratory services and biannual laboratory CD4 (LAB-CD4), biannual POC-CD4, and annual viral load in urban settings with laboratory services. We examine the impact of a range of values in sensitivity analyses, using Mozambique's 2014 per capita gross domestic product ($620) as a benchmark cost-effectiveness threshold.

Results: In rural settings, annual POC-CD4 compared to CLIN improves life expectancy by 2.8 years, reduces time on failed ART by 0.6 years, and yields an incremental cost-effectiveness ratio of $480/YLS. In urban settings, biannual POC-CD4 is more expensive and less effective than viral load. Compared to biannual LAB-CD4, viral load improves life expectancy by 0.6 years, reduces time on failed ART by 1.0 year, and is cost-effective ($440/YLS).

Conclusion: In rural settings, annual POC-CD4 improves clinical outcomes and is cost-effective compared to CLIN. In urban settings, viral load has the greatest clinical benefit and is cost-effective compared to biannual POC-CD4 or LAB-CD4. Tailoring ART monitoring strategies to specific settings with different available resources can improve clinical outcomes while remaining economically efficient.

Fig. 1. Mean time spent on suppressed and failed ART

Mean per person years spent suppressed (dark blue) and failed (red) on 1^st-line ART, and suppressed (light blue) and failed (orange) 2^nd-line ART for the rural setting (CLIN and POC-CD4₁₂, top) and urban setting (LAB-CD4₆, POC-CD4₆, and VL₁₂, bottom). We include the time initially suppressed and failed, as well as time re-suppressed and failed after an adherence intervention. Strategies do not sum to total life expectancy since time spent lost to follow-up is not included. The subscript indicates test frequency (e.g., POC-CD4₁₂ denotes monitoring every 12 months with POC-CD4). CLIN, clinical ART monitoring strategy; POC-CD4, point-of-care CD4 ART monitoring strategy; LAB, laboratory CD4 ART monitoring strategy; VL, HIV RNA ART monitoring strategy; ART, antiretroviral therapy.

Fig. 2. Heat maps of the ICER of POC-CD4₁₂ relative to CLIN

Heat maps of multi-way sensitivity analysis in the rural setting display the ICER of POC-CD4₁₂ relative to CLIN. Three panels are displayed, each showing results using different costs for POC-CD4 tests. On each panel, POC-CD4₁₂ random error increases left to right along the horizontal axes, and POC-CD4₁₂ bias becomes more negative down the vertical axes. The POC-CD4₁₂ base case value (from Scott et al [15], a POC-CD4 meta-analysis) is marked with an X. Other published estimates of POC-CD4 test bias and random error are marked with a cross (Diaw et al [35]), a four-pointed star (Glencross et al [22]), a circle (Jani et al, capillary [36]), a diamond (Jani et al, venous [36]), and a five-pointed star (Mtapuri et al [37]). LAB, laboratory; POC, point-of-care; ICER, incremental cost-effectiveness ratio; GDP, per capita gross domestic product.

Fig. 3. Budget impact analysis over 10 years for rural and urban settings

Budget impact analysis over a 10-year time horizon for the rural (CLIN and POC-CD4₁₂) and urban (LAB-CD4₆, POC-CD4₆, and VL₁₂) settings. Cumulative costs (2014 US$, millions) are on the vertical axis and include: clinical care (gray), 1^st-line ART (gold), 2^nd-line ART (blue), and monitoring costs (orange). Projected life expectancy for each strategy are shown in life years above each column. US$, US dollars; CLIN, clinical; POC, point-of-care; LAB, laboratory; VL, viral load; ART, antiretroviral therapy.