IGRA as a Predictive Factor of Silent Pulmonary Changes in Individuals Following Exposure to Tuberculosis

OBJECTIVES: We conducted a study on usefulness of the tuberculin skin test (TST) and the Quantiferon-TB Gold IT (QFT) tests as predictors of radiological changes after contact with tuberculosis. MATERIALS AND METHODS: The study group consisted of TB-exposed HCWs working in the Military Institute of Medicine (Warsaw, Poland). The usefulness of TST, QFT, and a combination of both tests was assessed for prediction of silent radiological findings. RESULTS: 83 previously TB-exposed participants were recruited. None of the participants had a history of active tuberculosis. Positive TST results were reported in 72 (86.8 %) participants, and positive QFTs were observed in 27 (32.5 %) cases. Chest radiographs revealed 23 findings specific for non-active tuberculosis in 18 (21.7 %) participants. The results of the QFTs were associated with the highest negative predictive value, positive predictive value, and positive likelihood ratio of silent chest X-ray findings suggestive of latent tuberculosis infection. Positive QFT was the only statistically significant variable that increases the odds ratio (OR–8.3) of the presence of typical of tuberculosis radiological changes in the lung. CONCLUSION: A positive QFT result in an individual with no TB history who was exposed to tuberculosis in the past is associated with a significantly higher risk of clinically silent parenchymal lesions in lungs suggestive of previous tuberculosis.