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Use of a T cell interferon gamma release assay in the investigation for suspected active tuberculosis in a low prevalence area.

Winqvist, Niclas LU ; Björkman, Per LU ; Norén, Ann and Miörner, Håkan LU (2009) In BMC Infectious Diseases 9(Jul 3).
Abstract
BACKGROUND: In settings with low background prevalence of tuberculosis (TB) infection, interferon-gamma release assays (IGRA) could be useful for diagnosing active TB. This study aims to evaluate the performance of QuantiFERON-TB Gold (QFT-G) in the investigation for suspected active TB, with particular attention to patients originating in high-incidence countries. Furthermore, factors associated with QFT-G results in patients with active TB were assessed. METHODS: From patients investigated for clinically suspected active TB, blood was obtained for QFT-G testing, in addition to routine investigations. Positive (PPV) and negative (NPV) predictive values for QFT-G were calculated, comparing patients with confirmed TB and those with other... (More)
BACKGROUND: In settings with low background prevalence of tuberculosis (TB) infection, interferon-gamma release assays (IGRA) could be useful for diagnosing active TB. This study aims to evaluate the performance of QuantiFERON-TB Gold (QFT-G) in the investigation for suspected active TB, with particular attention to patients originating in high-incidence countries. Furthermore, factors associated with QFT-G results in patients with active TB were assessed. METHODS: From patients investigated for clinically suspected active TB, blood was obtained for QFT-G testing, in addition to routine investigations. Positive (PPV) and negative (NPV) predictive values for QFT-G were calculated, comparing patients with confirmed TB and those with other final diagnoses. QFT-G results in TB patients originating from countries with intermediate or high TB incidence were compared with QFT-G results from a control group of recently arrived asymptomatic immigrants from high-incidence countries. Factors associated with QFT-G outcome in patients with confirmed TB were assessed. RESULTS: Among 141 patients, 41/70 (58.6%) with confirmed TB had a positive QFT-G test, compared to 16/71 (22.6%) patients with other final diagnoses, resulting in overall PPV of 71.9% and NPV of 67.6%. For patients with pulmonary disease, PPV and NPV were 61.1% and 67.7%, respectively, and 90.5% and 66.7% for subjects with extrapulmonary manifestations. Comparing patients from high-incidence countries with controls yielded a PPV for active TB of 76.7%, and a NPV of 82.7%. Patients with confirmed TB and positive QFT-G results were characterized by a lower median peripheral white blood cell count (5.9 x 10(9)/L vs. 8.8 x 10(9)/L; P < 0.001) and a higher median body mass index (22.7 vs. 20.7; P = 0.043) as compared to QFT-G-negative TB patients. CONCLUSION: The overall PPV and NPV of QFT-G for identifying active TB were unsatisfactory, especially for pulmonary disease. Thus, the usefulness of QFT-G for this purpose is questionable. However, a high PPV was observed for extrapulmonary TB and QFT-G might be considered in the diagnostic process in this situation. The PPV and NPV for identifying active TB among persons originating from regions with high-and intermediate TB incidence was similar to that observed in subjects originating in the low-incidence region. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
BMC Infectious Diseases
volume
9
issue
Jul 3
publisher
BioMed Central
external identifiers
  • WOS:000268569600001
  • PMID:19575781
  • Scopus:68049138081
ISSN
1471-2334
DOI
10.1186/1471-2334-9-105
language
English
LU publication?
yes
id
a1a410c9-6cc7-43f8-aee0-d828fcb386eb (old id 1453421)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/19575781?dopt=Abstract
date added to LUP
2009-08-04 10:37:38
date last changed
2016-10-13 04:33:14
@misc{a1a410c9-6cc7-43f8-aee0-d828fcb386eb,
  abstract     = {BACKGROUND: In settings with low background prevalence of tuberculosis (TB) infection, interferon-gamma release assays (IGRA) could be useful for diagnosing active TB. This study aims to evaluate the performance of QuantiFERON-TB Gold (QFT-G) in the investigation for suspected active TB, with particular attention to patients originating in high-incidence countries. Furthermore, factors associated with QFT-G results in patients with active TB were assessed. METHODS: From patients investigated for clinically suspected active TB, blood was obtained for QFT-G testing, in addition to routine investigations. Positive (PPV) and negative (NPV) predictive values for QFT-G were calculated, comparing patients with confirmed TB and those with other final diagnoses. QFT-G results in TB patients originating from countries with intermediate or high TB incidence were compared with QFT-G results from a control group of recently arrived asymptomatic immigrants from high-incidence countries. Factors associated with QFT-G outcome in patients with confirmed TB were assessed. RESULTS: Among 141 patients, 41/70 (58.6%) with confirmed TB had a positive QFT-G test, compared to 16/71 (22.6%) patients with other final diagnoses, resulting in overall PPV of 71.9% and NPV of 67.6%. For patients with pulmonary disease, PPV and NPV were 61.1% and 67.7%, respectively, and 90.5% and 66.7% for subjects with extrapulmonary manifestations. Comparing patients from high-incidence countries with controls yielded a PPV for active TB of 76.7%, and a NPV of 82.7%. Patients with confirmed TB and positive QFT-G results were characterized by a lower median peripheral white blood cell count (5.9 x 10(9)/L vs. 8.8 x 10(9)/L; P &lt; 0.001) and a higher median body mass index (22.7 vs. 20.7; P = 0.043) as compared to QFT-G-negative TB patients. CONCLUSION: The overall PPV and NPV of QFT-G for identifying active TB were unsatisfactory, especially for pulmonary disease. Thus, the usefulness of QFT-G for this purpose is questionable. However, a high PPV was observed for extrapulmonary TB and QFT-G might be considered in the diagnostic process in this situation. The PPV and NPV for identifying active TB among persons originating from regions with high-and intermediate TB incidence was similar to that observed in subjects originating in the low-incidence region.},
  author       = {Winqvist, Niclas and Björkman, Per and Norén, Ann and Miörner, Håkan},
  issn         = {1471-2334},
  language     = {eng},
  number       = {Jul 3},
  publisher    = {ARRAY(0x8a9e838)},
  series       = {BMC Infectious Diseases},
  title        = {Use of a T cell interferon gamma release assay in the investigation for suspected active tuberculosis in a low prevalence area.},
  url          = {http://dx.doi.org/10.1186/1471-2334-9-105},
  volume       = {9},
  year         = {2009},
}