RESEARCH ARTICLE Fluctuating Behavior and Influential Factors in the Performance of the QuantiFERON-TB Gold In-Tube Assay in the Diagnosis of Tuberculosis

Background The QuantiFERON-TB Gold In-Tube (QFT-GIT) is a newly developed but widely used inter-feron-γ release assay for diagnosing tuberculosis (TB). However, research has not deter-mined whether age or the use of an immune suppressive or anti-TB treatment influences this assay’s ability to detect TB. We assessed the QFT-GIT diagnostic performance for active tuberculosis (ATB) in children and adults in an endemic country and explored the effects of glucocorticoids and anti-TB therapy on the diagnostic value of the QFT-GIT. Methods A total of 60 children and 212 adults with suspected ATB were evaluated with the QFT-GIT. The association between the QFT-GIT diagnostic value and pretreatment factors was quali-tatively and quantitatively assessed. Results The sensitivity of the QFT-GIT was 83.9 % (95 % CI 66.3%-94.6%) in children, and 73.7% (95 % CI 57.8%-85.2%) in adults. Glucocorticoids affected the mitogen-stimulated respons