Table 1– Specificity for latent Mycobacterium tuberculosis infection (LTBI) diagnosis in individuals with very low risk for LTBI tested by QuantiFERON®-Gold In-Tube (QFT-G-IT) and/or T-SPOT®.TB assays
First author [ref.]Country (burden)ParticipantsIGRA(s) usedAge mean±sd# yrsSubjects assigned as low risk for M. tuberculosis infection nSubjects with negative tests/all tested subjects n/NSubjects considered false-positive nRounded specificity of IGRA(s)/TST % (95% CI)
Detjen 26Germany (low)Children with confirmed non-TB lymphadenitis (median 44) or respiratory infectionsT-SPOT®.TB/QFT-G-ITNTM infection: median 44 months; others: 52.5 months45T-SPOT®.TB: 39/40; QFT-G-IT: 40/40; TST: 22/40T-SPOT®.TB: 1; QFT-G-IT: 0; TST: 18 (all 18 with NTM lymphadenitis)T-SPOT®.TB: 98 (86.8–99.9); QFT-G-IT: 100 (92.8–100); TST: 55 (38.5–70.7)
Franken 27The Netherlands (low)Dutch Armed Forces personnelQFT-G-IT19.6±2.8171QFT-G-IT: 166/168+; TST: 136/145QFT-G-IT: 2; TST: 9QFT-G-IT: 99 (95.8–99.9); TST: 94 (88.6–97.1)
Palazzo 28Italy (low)Healthy blood donors as controls for TB suspectsQFT-G-ITBCG-unvacc.: 37.2±2; BCG-vacc.: 35.2±224QFT-G-IT: 14/14§; TST: NAQFT-G-IT: 0QFT-G-IT: 100 (80.7–100); TST: NA
Ruhwald 29Denmark (low)86 high school students and 38 high school staffQFT-G-ITStudents: 17.6±1.3; staff: 54.5±8.5124QFT-G-IT:124/124; TST: 116/124QFT-G-IT: 0; TST: 8QFT-G-IT: 100 (97.6–100); TST: 95 (87.7–97.2)
  • Pooled specificity of QFT-G-IT: 99.4% (95% CI 97.9–99.9%; Chi-squared (Q) = 2.90; degrees of freedom (df) = 3; p = 0.4069; inconsistency (I2) = 0.0%. Pooled specificity of tuberculin skin test (TST): 88.7% (95% CI 84.6–92.0%; Q = 2.90; df = 2; p = 0.0001; I2 = 94.5%). IGRA: interferon-γ release assay; TB: tuberculosis; NTM: nontuberculous mycobacteria; BCG: bacille Calmette–Guérin; unvacc.: unvaccinated; vacc.: vaccinated; NA: not assessed. #: unless otherwise stated; : after subtraction of invalid results/indeterminates; +: among recruits, five out of 171 results were QFT-G-IT-positive; of these recruits, two had previously been treated for tuberculosis and one was foreign-born without information on the tuberculosis prevalence in his home country, thus reducing the number of false-positive subjects and the number of tested persons eligible for analysis accordingly; §: 13 BCG-unvaccinated and one -vaccinated control persons, as shown in table 2 of the publication; evaluation of TST results was not performed because TST was perfomed in only seven out of the 14 persons included in the study.