H Lashkardoost, B Zeighami, M Mahmoudi, J Hassanzadeh, A Hamedi, Hr Tabatabaee, F Sameemanesh, Sm Kashfi,
Volume 6, Issue 1 (6-2010)
Abstract
Background & Objective: Because of uncertainty in interpretation of some tests for diagnosing TB, decision making for the tuberculosis treatment is based on multiple diagnostic tests. This study was conducted to assess the accuracy of Quanti FERON-TB Gold test in tuberculosis diagnosis.
Methods: The study was carried out on 30 cases and 46 controls. Statistical indices of sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratios, odds ratio and Receiver Operating Characteristics (ROC) curve were estimated.
Results: Sensitivity of QFT-G was 90.0% (95% CI=73.0-97.6), specificity 95.7% (95% CI=83.8-99.3), positive predictive value 93.1% (95% CI=76.3-98.9), negative predictive value 93.6% (95% CI=81.3-98.4). The area under ROC curve was 0.942 (95% CI=0.88-1.00), that significantly differed from chance diagonal area (P<0.0001). The optimum cut point for the Quanti FERON-TB Gold test was 0.35 IU/ml, with sensitivity of 0.90 and specificity of 0.957.
Conclusions: The Quanti FERON-TB Gold test displayed good validity indices in this study. Since the utility of this test has a high cost therefore this test would not be offered for routine tuberculosis detection. It suggested that this test are applicable for smear and culture negative tuberculosis, child tuberculosis, and assessment of TB contact tracing.
M Hashemi Shahri, A Fallah Ghajary, A Ansari Moghaddam, F Khadem Sameni, F Fayyaz Jahani, E Ahmadnezhad,
Volume 7, Issue 4 (3-2012)
Abstract
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Background & Objectives: Tuberculosis (TB) is an important issue which its
control is still unsatisfactory at global level. Traditional diagnostic
techniques for active TB diagnosis are inadequate: the diagnostic gold standard
is the cultural exam which suffers from lengthy processing and requires highly
specialized laboratories. Nowadays more specific tests have been recommended.
The aim of this study is to evaluate the performance of Quanti FERON-TB
(QFT)Gold In Tube-Test as a substitute for specific test tuberculin skin test
for diagnosis of latent tuberculosis infection in high risk groups.
Methods: One hundred thirty four (134) individuals who worked in Bo-Ali hospital
(Zahedan) enrolled in this study. They had no active tuberculosis. TST and QFT
tests were performed. The cut-off point of TST was considered based on 15 (mm)
or more indurations as positive. The result of QFT was evaluated by
manufactured guidelines. Multivariate logistic regression was used to identify
the putative risk factors of positive tests.
Results: Proportion of employees with latent TB were 111(82.8%) were positive by
either TST or QFT, and 76(56.7%) were positive by both tests. Agreement between
the tests was high (73.8%, k=0.39 95%CI:
0.21-0.44).
Positive family history of Tuberculosis was significant risk factor for both
positive tests.
Conclusion: This study showed high latent tuberculosis infection
prevalence in hospital workers and high agreement between TST and QFT. Decision
to select one of the tests will be depended on the population, purpose of study
and availability of resources. The results revealed that the QFT can be
appropriate alternative test for high risk group.
