Poor concordance between interferon-γ release assays and tuberculin skin tests in diagnosis of latent tuberculosis infection among HIV-infected individuals

• Type of Material: Article
• Authors: Naasha J. Talati, Emory University; Ulrich Seybold, Emory University; Bianca Humphrey, Emory University; Abiola Aina, Emory University; Jane Tapia, Emory University; Paul Weinfurter, Centers for Disease Control and Prevention; Rachel Albalak, Centers for Disease Control and Prevention; Henry Michael Blumberg, Emory University
• Language: English
• Date: 2009-02-10
• Publisher: BioMed Central
• Publication Version: Final Published Version
• Copyright Statement: ©2009 Talati et al; licensee BioMed Central Ltd.
• License: Creative Commons Attribution 2.0 Generic
• Final Published Version (URL): http://www.biomedcentral.com/1471-2334/9/15
• Title of Journal or Parent Work: BMC Infectious Diseases
• ISSN: 1471-2334
• Volume: 9
• Issue: 15
• Grant/Funding Information: Supported in part by Centers for Disease Control and Prevention (CDC) Tuberculosis Epidemiologic Studies Consortium (contract number 200-2001-00086), the CDC Foundation, and the Emory Center for AIDS Research (P30 AI050409).
• Research Categories: Health Sciences, Immunology; Health Sciences, Public Health; Health Sciences, General

Abstract

Background A new generation of diagnostic tests, the interferon-γ release assays (IGRAs), have been developed for the detection of latent tuberculosis infection (LTBI). Limited data are available on their use in HIV-infected persons. Methods A cross-sectional study was carried out at 2 HIV clinics in Atlanta to assess the utility of two IGRA tests (T-SPOT.TB [TSPOT] and QuantiFERON-TB Gold in Tube [QFT-3G]) compared to the tuberculin skin test (TST). Results 336 HIV-infected persons were enrolled. Median CD4 count was 335 cells/μl and median HIV viral load was 400 copies/ml. Overall, 27 patients (8.0%) had at least 1 positive diagnostic test for LTBI: 7 (2.1%) had a positive TST; 9 (2.7%) a positive QFT-3G; and 14 (4.2%) a positive TSPOT. Agreement between the 3 diagnostic tests was poor: TST and TSPOT, [κ = 0.16, 95% CI (-0.06, 0.39)], TST and QFT-3G [κ = 0.23, 95% CI (-0.05, 0.51)], QFT-3G and TSPOT [κ = 0.06, 95% CI (-0.1, 0.2)]. An indeterminate test result occurred among 6 (1.8%) of QFT-3G and 47 (14%) of TSPOT tests. In multivariate analysis, patients with a CD4 ≤ 200 cells/μl were significantly more likely to have an indeterminate result [OR = 3.6, 95% CI (1.9, 6.8)]. Conclusion We found a low prevalence of LTBI and poor concordance between all 3 diagnostic tests. Indeterminate test results were more likely at CD4 counts ≤ 200 cells/μl. Additional studies among HIV-infected populations with a high prevalence of TB are needed to further assess the utility of IGRAs in this patient population.