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Background: The Visitect CD4 Advanced Disease test (AccuBio, Alva, United Kingdom) is a rapid, semi-quantitative assay that estimates CD4 results above or below 200 cells/μL. We evaluated the performance of the Visitect CD4 assay in semi-urban laboratories in Uganda., Methods: We performed a pragmatic laboratory validation of the Visitect CD4 platform in four routine HIV clinics in Uganda, nested within a cluster randomized trial evaluating an enhanced package of screening and treatment for persons with advanced HIV disease (NCT05085171). As part of the clinical trial, samples processed on the Visitect CD4 platform were confirmed using another CD4 testing method. We compared the diagnostic performance of the Visitect CD4 platform against the confirmatory method by evaluating the sensitivity, specificity, positive and negative predictive values., Results: Of 1495 venous blood samples that were processed both by the Visitect CD4 test and another confirmatory CD4 platform at clinics in Kampala, Uganda, specificity was 81% (95% CI, 79%-84%) and the positive predictive value was 69% (95% CI, 66%-73%). There were no samples for which the Visitect test was >200 cells/μL and the confirmatory test was ≤200 cells/μL, resulting in a sensitivity of 100%. Among Visitect CD4 tests that were read as <200 cells/μL with confirmatory results >200 cells/μL, the median confirmatory CD4 result was 397 (IQR, 281-590) cells/μL. Specificity varied by clinic ranging from 63% to 99%., Conclusions: Given variable specificity of the Visitect CD4 Advanced Disease platform, successful implementation will require consideration of clinic context and laboratory staffing., Competing Interests: The authors report no conflicts of interest related to this work., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

A newly developed cryptococcal antigen (CrAg) semiquantitative (SQ) lateral flow assay (LFA) provides a semiquantitative result in a rapid one-step test instead of performing serial dilutions to determine CrAg titer. We prospectively compared the diagnostic performance of the CrAgSQ assay (IMMY) with the CrAg LFA (IMMY) on cerebrospinal fluid (CSF) samples collected from persons with HIV-associated meningitis. The CrAgSQ grades (1+ to 5+) were compared with CrAg LFA titers and quantitative CSF fungal cultures. Among 87 participants screened for HIV-associated meningitis, 60 had cryptococcal meningitis (59 CrAg positive [CrAg + ] by LFA and 1 false negative due to prozone with CrAg LFA titer of 1:1,310,000 and culture positivity), and 27 had no cryptococcal meningitis by CrAg LFA or culture. The CrAgSQ on CSF had 100% (60/60) sensitivity and 100% specificity (27/27). CSF CrAg titers ranged from 1:5 to 1:42 million. CrAgSQ grades of 1+, 2+, 3+, 4+, and 5+ corresponded to median CrAg LFA titers of 1:<10, 1:60, 1:7,680, 1:81,920, and 1:1,474,000, respectively. CSF CrAgSQ grades 3+ or higher were always CSF culture positive. Mortality at 14 days for those with low CrAgSQ grade (1+ to 3+) was 5% (1/22) versus 21% (8/38) with high CrAgSQ grades (4+ to 5+) ( P  = 0.084). The CrAgSQ demonstrates excellent diagnostic performance, maintaining both the sensitivity and specificity of the CrAg LFA, and counters false-negative prozone effects. The CrAgSQ assay reading is more complex but does provide useful clinical information about disease burden and probability of culture positivity in a single rapid diagnostic test.