Indus Hospital & Health Network Karachi, Sindh, Pakistan
Background/Case Studies: FDA guidance for HIV blood donor screening requires multilayered testing, HIV Ag/Ab chemiluminescent microparticle immunoassay (CMIA) and nucleic acid testing (NAT) with supplemental testing algorithms for discrepant results. This resolves diagnostic discrepancies, ensuring accurate donor notification. FDA guidance recommends BioRad Geenius HIV1/2 confirmatory assay as a supplemental test. However, implementation challenges exist, including high cost and recently encountered challenge of availability. This study evaluates the performance of Geenius and 3 rapid diagnostic tests (RDT) using quantitative PCR (qPCR) as a gold standard.
Study
Design/Methods: At 6 centers of the Indus Hospital and Health Network in Pakistan (Karachi, Jamshoro, Hyderabad, Thatta, Multan, and Bahawalpur), a prospective cohort of 188,665 donors was screened from Nov 2023 – Mar 2025, and 202 donors (0.11%) were repeatedly reactive on the Abbott Architect CMIA HIV Combo, out of which 94 (0.05%) were positive on Grifols Panther Procleix Ultrio Elite NAT. Viral loads were measured by Cobas HIV-1 qPCR test. True positives (TP), CMIA+, NAT+ and PCR+ and false positives (FP) CMIA+, NAT- and PCR- were identified. All samples were tested on Geenius and three RDTs; Lab Diagnostic Systems R-Test HIV1/2 Rapid test, Zhejiang Orient Gene Biotech Acu-Check HIV 1/2 and Abbott Determine HIV 1/2. Performance characteristics of various HIV assays in comparison with qPCR were evaluated. HIV CMIA and NAT negative samples (n=202) were also tested with RDTs. Geenius and RDTs were evaluated for supplemental testing by CMIA + and NAT – cases in terms of PPV and reagent cost. Furthermore, an S/CO cut-off was determined for HIV Ag/Ab Combo CMIA, identifying TP for possible elimination of supplemental testing in these cases.
Results/Findings: In this study, 94 (0.05%) and 108 (0.06%) samples were confirmed TP and FP on CMIA respectively when compared to the gold standard (qPCR). Performance characteristics of various HIV assays in comparison with the qPCR are shown in Table 1. All RDTs were positive between the viral loads of 61 – 3940000 copies/ml with one exception being negative by 3 RDTs and Geenius while being CMIA reactive (mean S/CO 4.28), NAT positive with qPCR viral load of 540 copies/ml. The reagent cost of Acu-Check, R-Test and Determine was 98%, 99% and 97% less than Geenius, respectively. There was no correlation between S/CO value and qPCR (r=0.15) thus S/CO has no value in avoiding supplemental testing. However, at the CMIA S/CO (mean) values of 16.45 and 278.51, the PPV was 95% and 100%, respectively. Conclusions: Our study reveals an HIV prevalence of 0.05% in blood donors in Pakistan. RTDs demonstrate a PPV comparable with Geenius™ HIV-1/2 confirmatory assay with Acu-Check showing equivalent results followed by R-Test and Determine. These tests not only provide a cost effective solution but are also easily available.
