Aims To compare the agreement between the QuantiFERON-TB GOLD In Tube (QTF) test and the tuberculin skin test (TST) in BCG-vaccinated and non‑vaccinated children with suspected latent tuberculosis (TB) infection (LTBI) or TB disease (TBD), with and without risk factors for TB.
Methods A multicentre, prospective study, excluding immunocompromised children, was performed in nine hospitals in Madrid, Spain. TST and QTF were performed in immigrants, TB contacts and patients with TBD. The results were analysed according to risk factors, clinical and radiological findings.
Results 459 children were included: 318 were considered non-infected, 73 were diagnosed with LTBI and 68 with TBD. QTF indeterminate results (20/459; 4.3%) were obtained because of low production of interferon γ. Analysing positive and negative results of TST and QTF, disagreement was more frequently observed among LTBI cases (54%; 38/70) than in non-infected or TBD cases (0.8%; 3/369) (p<0.01). There were more negative QTF results among BCG-vaccinated children with LTBI (76%) than in unvaccinated LTBI cases (23%). LTBI cases with a negative QTF had a smaller TST size (12.7±4.7 mm) than those with a positive QTF (17.9±5.7 mm) (p<0.01). Agreement between tests in BCG-vaccinated children (κ=0.47) was lower than in non-vaccinated cases (κ=0.91) (p<0.05). Tests in children exposed to TB showed better agreement (κ=0.76) than in children not exposed to TB (κ=0.44) (p<0.05).
Conclusions Agreement of both tests was excellent in TBD cases, non-vaccinated children and non-infected patients. An important number of QTF-negative results were observed among LTBI cases, especially in BCG-vaccinated children. Agreement was better in children who were at risk of TB infection (exposed children).
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Competing interest None.
Patient consent Obtained.
Ethics approval This study was conducted with the approval of the Carlos III Hospital's Ethics Committee (Main Investigation Centre). Subsequently it was approved by the rest of the Hospitals’ Ethics Committees.
Provenance and peer review Not commissioned; externally peer reviewed.