BACKGROUND: Little is known about the QuantiFERON-TB Gold In-Tube Test (QFT) in extreme age groups. The test performance has been reported to be impaired in children and elderly, but reports are diverging. The aim of this study was to evaluate QFT performance in patients with and without Tuberculosis (TB).

METHODS: A retrospective study analysing the results of 18,850 QFT performed in Denmark 2005-2010. The effect of age, sex, localisation of TB, and result of culture on QFT performance (positive, negative and indeterminate results) was determined.

RESULTS: Among 383 patients with TB, indeterminate rate was low (3.9%, 15/383). Sensitivity was high (86.1%, 317/368) and not affected by sex or localization of TB disease, but declined with increasing age (p < 0.0001). In children 1-4 years old, sensitivity was high (100%, 9/9). Among 15,709 persons without TB, the indeterminate rate was 5.1% (804/15,709) and significantly higher in infants <1 year (15.6%, 5/32) and elderly >65 years (8.1%, 219/2715) compared to the adult population 15-64 years (4.5%, 552/12,317). Indeterminate results were due to a low positive control in 99.6% (801/804).

CONCLUSION: In Denmark, a TB low incidence country, the overall QFT performance was good. The sensitivity in children (≥ 1) was high although few children were included, whereas sensitivity declined with increasing age. Indeterminate rates were higher in infants and elderly. In contrast to current guidelines, our data suggest that the QFT performs well in children ≥ 1 years in low endemic regions but that the test should be used with care among the elderly.