Agreement between Tuberculin Skin Test (TST) and QuantiFERON-TB Gold In-Tube (QFT) Assay When Screening for Latent Tuberculosis Infection (LTBI) in Young Refugee Children Open Access

Fell, Ashley (2013)

Permanent URL: https://etd.library.emory.edu/concern/etds/6d56zx40r?locale=en
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Abstract

Since the early 2000's, foreign-born individuals have begun to make up a majority of cases of TB in the United States. Most of these cases result from the reactivation of latent tuberculosis infection (LTBI). Young children with LTBI are at particularly high risk of reactivation. Recently, interferon-gamma release assays (IGRAs) have been developed as a blood test for LTBI, providing an alternative to traditional tuberculin skin testing (TST). This cross sectional study sought to characterize agreement between QuantiFERON®-TB Gold In-Tube (QFT) and TST results while screening for LTBI in 216 refugee children less than 5 years of age in DeKalb County, Georgia. Medical record review was used to extract relevant test results and characteristics of participants.

Only 11% (4/37) of TST-positive children were QFT-positive and nearly 20% of all children had discordant TST/QFT results. Overall agreement between QFT and TST results was 81% but the kappa statistic indicated very poor concordance (κ=0.09, 95% Confidence Interval (CI): -0.05, 0.23). Concordance was higher in the subset of children 24 months of age or older (Agreement=86%, κ=0.22, 95% CI: -0.01, 0.44). The high discordance of TST and QFT results is likely explained by the high rate of Bacille Calmette-Guerin (BCG) vaccination in the study population and relatively low prevalence of LTBI. Once the use of IGRAs in this population is better understood, testing for LTBI could become simpler and more cost-effective, improving TB control in the United States.

Table of Contents

Table of Contents

Introduction................................................................... 1
Methods........................................................................ 5
Results.......................................................................... 9
Discussion..................................................................... 12
References.................................................................... 14
Figures and Figure Legends.............................................. 17

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