Title: PA-738 Evaluation of QIAreach QuantiFERON-TB lateral-flow nanoparticle fluorescence assay for TB infection testing among TB household contacts in three high-burden settings
Abstract: <h3>Background</h3> Tuberculosis infection (TBI) testing and treatment are fundamental to achieve TB elimination ambitions. Among household contacts (HHCs) of TB patients, the uptake of TBI testing is limited, in part due to a lack of gold standard test and challenges associated with implementation, which vary by available tests. Our study evaluated the prevalence of TBI among HHCs and determined concordance of QuantiFERON-TB-Gold-Plus (QFT-Plus) to QIAreach QuantiFERON-TB (QIAreach), a new field-friendly lateral-flow-nanoparticle-fluorescence assay. <h3>Methods</h3> In a cross-sectional study in Lesotho, South Africa and Tanzania, blood samples were collected from HHCs at an initial household visit using a single lithium heparin tube for paired QFT-Plus and QIAreach processing, testing and interpretation following manufacturer’s guidelines. TBI prevalence was determined using QFT-Plus result. We assessed percentage agreement between QFT-Plus and QIAreach using Cohen’s Kappa. <h3>Results</h3> We enrolled 964 HHCs [321 in Lesotho, 300 in South Africa, and 343 in Tanzania]. Of this, 465 HHCs had paired results, of whom 65% (302/465) were females with a median age of 27 years (interquartile range: 13, 45). TBI prevalence was 51% (236/465). Among HHCs with paired results, 42% (197/465) were positive and 34% (156/465) negative on both assays, while 24% (112/465) had discordant results. Total agreement was 78% [353/451, 95% Confidence Interval (CI): 74 – 82, kappa = 0.5627, p<0.001] with a positive agreement of 77% (197/255, 95% CI: 71 – 82) and a negative agreement of 80% (157/195, 95% CI: 74 – 85). <h3>Conclusion</h3> Among HHCs in three high-burden countries, we identified a high TBI prevalence. QIAreach demonstrated a moderate concordance against QFT-Plus. However, in the absence of a gold standard test, it is difficult to interpret the implication of this finding. Further research is needed to understand its usability in this population, specifically if it addresses field implementation challenges associated with similar TBI tests.