Table 4

True- and false-positive resultsa when changing from QFT-IT to T-Spot in screening for LTBI
Country LTBI prevalenceb Increase in true positivesa,c Increase in false positivesa,c Increase in false positives for every true positive gained
United States 4.70% 329 12,389 37.7
Mexico 28.82% 2,018 9,253 4.6
Brazil 38.74% 2,712 7,964 2.9
Thailand 46.74% 3,272 6,924 2.1
Ivory Coast 54.62% 3,823 5,900 1.5

LTBI, latent tuberculosis infection; QFT-IT, QuantiFERON-TB Gold In-Tube; T-Spot, T-SPOT.TB.

a Based on a hypothetical population of 100,000 tested individuals.

b Source: World Health Organization Global TB Database [4].

c Sensitivity estimates: QFT-IT 81%, T-Spot 88%; specificity estimates: QFT-IT 99%, T-Spot 86%.

Bentley et al.

Bentley et al. BMC Research Notes 2012 5:563   doi:10.1186/1756-0500-5-563

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