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Updated: May 9, 2025
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Published on: October 31, 2010
Lateral flow assay-based CD4 cell count testing for advanced HIV disease
Zibusiso Ndlovu1, Ana Moore2, Esther C Casas3
1Southern African Medical Unit, Médecins Sans Frontières, Cape Town, South Africa; Division of Epidemiology and Biostatistics, Department of Global Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.
Insights
Point-of-care CD4 testing instruments are being discontinued, impacting advanced HIV disease (AHD) diagnosis. CD4 lateral flow assays (LFA) offer a potential screening solution, but performance varies by sample type.
Area of Science:
- Clinical diagnostics
- HIV/AIDS research
- Public health
Background:
- Global policy shifts de-emphasize CD4 testing, leading to reduced investment.
- Discontinuation of major CD4 testing instruments threatens advanced HIV disease (AHD) diagnosis.
- High mortality from AHD persists, necessitating improved diagnostic strategies.
Purpose of the Study:
- To evaluate the potential of CD4 lateral flow assay (LFA) testing for pragmatic AHD screening.
- To consider the interplay of diagnostic performance, accessibility, and cost-effectiveness for AHD screening.
- To inform implementation science and policy development for reducing HIV mortality.
Main Methods:
- Review of published studies on Visitect CD4 LFA test performance.
- Analysis of diagnostic accuracy (sensitivity, specificity) in venous and fingerprick samples.
- Consideration of test attributes beyond clinical accuracy, including turnaround time and decentralization feasibility.
Main Results:
- Visitect CD4 LFA shows moderate-to-high diagnostic performance in venous blood (Sensitivity: 93.4-95.0%, Specificity: 81.9-87.7%).
- Specificity is substantially lower in fingerprick samples (61.4-78.3%).
- Diagnostic yield, cost-effectiveness, and accessibility are critical factors for AHD screening.
Conclusions:
- CD4 LFA testing presents a pragmatic approach for AHD screening, particularly given the decline in traditional CD4 testing.
- Optimizing LFA implementation requires balancing diagnostic accuracy with practical attributes and AHD prevalence.
- Further research and policy development are crucial to leverage LFA for reducing long-term HIV mortality.
Abstract:
The global policy shift to treating all people living with HIV, regardless of CD4 cell count, has inadvertently led donors and national programmes to reduce their investments in CD4 testing. The subsequent decline in testing volumes has caused manufacturers to discontinue major point-of-care CD4 testing instruments, despite these tests being crucial for the diagnosis of advanced HIV disease (AHD). Mortality from AHD remains high, with an estimated 630 000 deaths among people living with HIV in 2023. CD4 lateral flow assay (LFA) testing could provide pragmatic screening for AHD. Published studies show moderate-to-high diagnostic performance of Visitect CD4 LFA tests in venous blood samples, with a sensitivity of 93·4-95·0% and specificity of 81·9-87·7%, but the specificity from fingerprick samples is substantially lower (61·4-78·3%). Therefore, the interplay between diagnostic test performance, other attributes (eg, result turnaround time, accessibility, feasibility of decentralisation, cost-effectiveness, and diagnostic yield), and AHD prevalence needs to be considered. Given its potential to cost-effectively support and increase AHD screening, and to subsequently assist in long-term reductions in HIV mortality beyond 2030 UNAIDS targets, a greater appreciation of the diagnostic yield of LFA-based CD4 testing is crucial. Implementation science and policy development should consider public health impacts in addition to test clinical accuracy.
