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|Title: ||Commercial Interferon Gamma Release Assays Compared to the Tuberculin Skin Test for Diagnosis of Latent Mycobacterium tuberculosis Infection in Childhood Contacts in the Gambia|
|Authors: ||Adetifa, Ifedayo M. O.|
Ota, Martin O. C.
Jeffries, David J.
Lugos, Moses D.
Adegbola, Richard A.
Hill, Philip C.
latent tuberculosis infection
|Issue Date: ||2010|
|Publisher: ||The Pediatric Infectious Disease Journal|
|Series/Report no.: ||Vol. 29;No. 5; Pp 439 - 443|
|Abstract: ||Background: We compared the performance of tuberculin skin test (TST),
Quantiferon-TB Gold in-tube (QFT-GIT), and T-SPOT.TB in diagnosing
latent tuberculosis (LTBI) among childhood TB contacts in a TB endemic
setting with high BCG coverage. We evaluated the performance of interferon
gamma release assays (IGRAs) and TST when combined in an algorithm.
Methods: Childhood contacts of newly diagnosed TB patients were tested
with TST, QFT-GIT, and T-SPOT. The level of exposure in contacts was
categorized according to whether they slept in the same room, same house,
or a different house as the index case. For the evaluation of combined test
performance, prior estimates for prevalence of latent TB were used in
Bayesian models that assumed conditional dependence between tests.
Results: A total of 285 children were recruited. Overall, 26.5%, 33.0%, and
33.5% were positive for TST, T-SPOT, or QFT-GIT, respectively. All 3 tests
responded to the gradient of sleeping proximity to the index case. Neither TST
nor IGRA results were confounded by BCG vaccination. There was moderate
agreement ( 0.40–0.68) between all 3 tests. Combination of either IGRA
with TST increased sensitivity (by 9.3%–9.6%) especially in contacts in the highest
exposure category but was associated with loss of specificity (9.9%–11.3%).
Conclusion: IGRAs and TST are similar in their diagnostic performance for
LTBI. An approximate 10% sensitivity benefit for using the TST and an IGRA
in combination is associated with a slightly greater specificity loss. Testing
strategies combining an IGRA and TST with an “or” statement may be useful
only in situations where there is a high pretest probability of latent infection.|
|Appears in Collections:||Medical Laboratory Sciences|
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