P-274. An Assessment of the Agreement between Qualitative and Quantitative Measures of CD4 Counts Amongst Persons Screened for an Advanced HIV Clinical Trial in Nigeria

TL;DR

This study compares a rapid qualitative CD4 test with a gold-standard quantitative test in Nigeria to assess their agreement in identifying HIV patients with low CD4 counts.

Contribution

The study evaluates the accuracy of a point-of-care CD4 test against quantitative flow cytometry in a real-world clinical setting in Nigeria.

Findings

The qualitative POC CD4 test correctly identified 78.1% of participants with CD4 counts ≤200 cells/mm³.

The test misclassified 94 participants who actually had CD4 counts >200 cells/mm³ based on the gold standard.

The study suggests that qualitative CD4 testing should complement, not replace, quantitative testing in clinical decisions.

Abstract

Advanced HIV disease (AHD) is of great concern in developing countries like Nigeria. Nigeria implemented an AHD package of care that includes rapid qualitative point-of-care (POC) CD4 testing to identify individuals with CD4 counts ≤200 cells/mm3, guiding further screening (e.g. TB lipoarabinomannan and cryptococcal antigen tests). However, the accuracy of this qualitative method compared to gold-standard quantitative CD4 testing via flow cytometry remains uncertain. We aimed to evaluate the agreement between POC qualitative CD4 testing and gold standard for detecting CD4 counts ≤200 cells/mm3

Data were collected retrospectively from records of individuals who had been screened for an AHD clinical trial from February to November 2024 at antiretroviral therapy (ART) clinics of 7 tertiary hospitals across 5 geo-political zones in Nigeria. Persons newly found to have acquired HIV or had interrupted treatment for at least 6 months were screened with a rapid POC qualitative CD4 assay as standard of care. Those with CD4 count ≤200 cells/mm3 according to the POC assay subsequently had quantitative CD4 testing as screening for the trial.

A total of 430 participants with a mean age of 40.8 years (±13.9 SD) were enrolled. A slight majority were females, 226(52.6%), and the Lagos University Teaching Hospital had the most participants [206(47.9%)]. Thirteen participants also had tuberculosis, while 1 each was found to have Hepatitis B and cryptococcal meningitis respectively. The qualitative POC CD4 method correctly identified 336(78.1%) out of 430 participants as having CD4 ≤200 cells/mm3 while misclassifying 94 out of 430 participants that actually had CD4 >200 cells/mm3 based on the gold standard.

The qualitative POC CD4 method provides a rapid and cost-effective alternative to the gold standard but shows limitations, particularly near critical thresholds (≤200 cells/mm3). These limitations may impact clinical decisions and outcomes, suggesting the need for confirmatory quantitative testing where feasible. Rapid qualitative methods should complement, not replace, quantitative CD4 testing, especially in resource-limited settings where accurate risk stratification for treatment decisions are critical.

All Authors: No reported disclosures