@article{20da3b47de9a4eb18b2142f2a6f07762,
title = "The impact of HIV infection and CD4 cell count on the performance of an interferon gamma release assay in patients with pulmonary tuberculosis",
abstract = "BACKGROUND: The performance of the tuberculosis specific Interferon Gamma Release Assays (IGRAs) has not been sufficiently documented in tuberculosis- and HIV-endemic settings. This study evaluated the sensitivity of the QuantiFERON TB-Gold In-Tube (QFT-IT) in patients with culture confirmed pulmonary tuberculosis (PTB) in a TB- and HIV-endemic population and the effect of HIV-infection and CD4 cell count on test performance. METHODOLOGY/PRINCIPAL FINDINGS: 161 patients with sputum culture confirmed PTB were subjected to HIV- and QFT-IT testing and measurement of CD4 cell count. The QFT-IT was positive in 74% (119/161; 95% CI: 67-81%). Sensitivity was higher in HIV-negative (75/93) than in HIV-positive (44/68) patients (81% vs. 65%, p = 0.02) and increased with CD4 cell count in HIV-positive patients (test for trend p = 0.03). 23 patients (14%) had an indeterminate result and this proportion decreased with increasing CD4 cell count in HIV-positive patients (test for trend p = 0.03). Low CD4 cell count (<300 cells/microl) did not account for all QFT-IT indeterminate nor all negative results. Sensitivity when excluding indeterminate results was 86% (95% CI: 81-92%) and did not differ between HIV-negative and HIV-positive patients (88 vs. 83%, p = 0.39). CONCLUSIONS/SIGNIFICANCE: Sensitivity of the QFT-IT for diagnosing active PTB infection was reasonable when excluding indeterminate results and in HIV-negative patients. However, since the test missed more than 10% of patients, its potential as a rule-out test for active TB disease is limited. Furthermore, test performance is impaired by low CD4 cell count in HIV-positive patients and possibly by other factors as well in both HIV-positive and HIV-negative patients. This might limit the potential of the test in populations where HIV-infection is prevalent.",
keywords = "Adult, Biochemistry, CD4-Positive T-Lymphocytes, Female, HIV Infections, HIV Seropositivity, Humans, Interferon-gamma, Male, Prevalence, Reagent Kits, Diagnostic, Sensitivity and Specificity, Sputum, Tanzania, Tuberculosis, Pulmonary",
author = "Aabye, {Martine G} and Pernille Ravn and George PrayGod and Kidola Jeremiah and Apolinary Mugomela and Maria Jepsen and Daniel Faurholt-Jepsen and Nyagosya Range and Henrik Friis and John Changalucha and Andersen, {{\AA}se Beng{\aa}rd}",
year = "2009",
doi = "10.1371/journal.pone.0004220",
language = "English",
volume = "4",
pages = "e4220",
journal = "PLOS ONE",
issn = "1932-6203",
publisher = "Public Library of Science",
number = "1",
}