Comparison of Mantoux and QuantiFERON TB Gold Tests for Diagnosis of Latent Tuberculosis Infection in Army Personnel
Results for both TST and QFT-GIT were available for 676 subjects, 20.6% of whom had a positive TST at a cutoff of 10mm and...when using 15 mm as the cutoff, the agreement was 92%
Screening for tuberculosis infection among newly arrived asylum seekers: Comparison of QuantiFERON®TB Gold with tuberculin skin test
Overall kappa-values for agreement between QFT and TST were fair to moderate depending on the chosen cut-off values for TST, and they were highest with TST cut-off ≥ 10 mm
Preliminary results on the use of QuantiFERON TB Gold (In-tube method) in a large cohort study of TB in adolescents in South Africa
Agreement between TST and QFT in this cohort at baseline varied according to TST cutoff.
We now have a study from Norway which finds that, in children, QFT agreement has some relation to TST cutoff but it was not meaningful;
Most children (79%) had TST reactions in the range of 6-14 mm; 5% of these were QFT positive...Discrepant results between the tests were common even for TST reactions above 15 mm, as only 22 % had a positive QFT.
It would appear that the TST is adversely affected by environmental conditions whilst the QFT is not and QFT gives a consistent result in any location.
The results support the assumption that factors other than tuberculosis infection are widely contributing to positive TST results in this group and indicate the improved specificity of QFT for latent tuberculosis.
Pediatricians and policy makers need to take note of the results; relying on the TST diagnosis for any cutoff could expose otherwise healthy children to an unnecessary treatment which has attendant risks including those of hepatoxicity and mortality
Among 511 TST positive children only 9% (44) had a confirmed positive QFT result.
