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Comparison of Advanced HIV Disease identification using CD4 results from a semi-quantitative CD4 point of care test and CD4 flow cytometry in Nigeria

Title
Comparison of Advanced HIV Disease identification using CD4 results from a semi-quantitative CD4 point of care test and CD4 flow cytometry in Nigeria
Presenter
Nere Otubu
Authors
N. Otubu * (1), O. Abudiore (1), M.-M. Akanmu (1), B. Levy-Braide (1), W. Eigege (1), O. Sowale (1), A. Inyang (1), D. Rathakrishnan (2), I. Amamilo (1), J. Conroy (3), F. Lufadeju (1), C. Amole (3), O. Wiwa (4), P. Nwaokenneya (5), C. Adesigbin (5), A. Ikpeazu (5), G. Olorunfemi (6), R. Oladele (7), O. Agbaji (8), S. Akanmu (7)
Institutions
(1) Clinton Health Access Initiative, HIV Access Program, Abuja, Nigeria, (2) Clinton Health Access Initiative, HIV Access Program, Kigali, Rwanda, (3) Clinton Health Access Initiative, HIV Access Program, Boston, United States, (4) Clinton Health Access Initiative, Global Resources for Health, Abuja, Nigeria, (5) Federal Ministry of Health, National AIDS and STIs Control Program, Abuja, Nigeria, (6) University of Witwatersrand, Division of Epidemiology & Biostatistics, Johannesburg, South Africa, (7) Lagos University Teaching Hospital, Lagos, Nigeria, (8) Jos University Teaching Hospital, Jos, Nigeria

BACKGROUND: CD4 testing is critical in identifying people living with HIV with Advanced HIV Disease (AHD) and is conducted at enrollment/re-enrollment into care. Nigeria introduced VISITECT CD4 Advanced Disease rapid test (VISITECT), a semi-quantitative point of care test pre-qualified by WHO, to address gaps in CD4 coverage. Conducting VISITECT test requires time-sensitive procedural steps and visual acuity for interpretation, and there was no experience with its use in Nigeria. To allay concerns of the impact of operational differences on the quality of VISITECT results in the Nigerian context, we compared results from VISITECT to CD4 flow cytometry, the current gold standard in-country.
METHODS: We recruited patients >10years old enrolling into HIV care across 4 states (Akwa-Ibom, Anambra, Lagos, Rivers) implementing the AHD package of care between February and June 2021. Venous or capillary blood samples were collected at enrollment, and parallel CD4 tests were conducted via VISITECT and CD4 flow cytometry platforms (BD FACSPresto and Partec Cyflow). We determined how many results reported by healthcare workers (HCWs) as <200cells/mm3 (AHD), or '¥200cells/mm3 by CD4+ cell flow cytometry was correctly identified by VISITECT. The paired tests were tested for agreement using Cohen's Kappa test.STATA version 16 was used for analysis.
RESULTS: 603 patients were recruited from 10 ART facilities. The prevalence of CD4 <200cells/mm3 was 47.6%, (95% CI: 43.6% - 51.6%, 287/603) and 50.9% (95% CI: 46.9% - 54.9%, 307/603) on the flow cytometry and VISITECT respectively. In all, 268 of 307 VISITECT results that were <200cells/mm3 were identified as correct by the gold standard, giving a positive predictive value of 87.3%. 277 of 296 VISITECT results '¥200cells/mm3 were identified as correct by the gold standard, with giving a negative predictive value of 93.6% (Kappa = 0.81, Agreement =90.38%, P= <0.001).
CONCLUSIONS: The observed high agreement between VISITECT and flow cytometry results demonstrates that VISITECT can correctly identify patients with AHD and has the potential to improve access to CD4+ testing and linkage to care. The findings show that operational differences have minimal effect on the accuracy of VISITECT results at facilities and Nigeria can deploy the test across the country with minimal concerns.

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