despite its objectivity and its higher specificity (especially in Bacille Calmette-Guérin vaccinated children), the real place of QFT-G IT in TB diagnosis in children remains difficult to define.To put QFT into context, they did say that
TB diagnosis in children is particularly difficult. Clinical, radiologic, and bacteriologic features of TB disease are uncommon in children: lack of typical symptoms (Marais et al., 2006), difficulty of chest radiography (Swingler et al., 2005), and paucibacillary specimens (Schaaf et al., 1995).
Less than one-half of active TB in children is culture proven, and polymerase chain reaction (PCR), despite its rapidity and its sensitivity, is unable to improve on this (Gomez-Pastrana et al., 1999; Marais and Pai, 2007).
Diagnosis of latent TB infection (LTBI) is largely based on the tuberculin skin test (TST). However, intradermal administration is difficult to perform. The TST is also characterized by its subjective reading and its lack of sensitivity and specificity.
Children BCG vaccinated or infected with nontuberculous mycobacteria (NTM) can have false-positive TST reactions. Moreover, children presented with malnutrition, measles, HIV, or other infections often have false-negative TST but real TB infections (Marais, 2008).
Thus, none of these approaches (clinical, radiologic, bacteriologic, and TST) are really accurate. That could lead either to overdiagnosis (children unnecessarily treated for TB) or to underestimation (more frequent active TB disease) of TB.The following Table indicates that for this study the performance of QFT-GIT was more comparable with the active TB gold standard, sputum culture
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