Background.The interferon−g−release assays (IGRA) are emerging as an attractive alternative to the tuberculin skin test (TST)
for the diagnosis of latent tuberculosis infection (LTBI).The absence of a gold standard for LTBI hampers the assessment of any
diagnostic test.
Methods.In a prospective study,229 patients (mean age 35.5±24.6 y) from different ward of the Hospital (Respiratory
Diseases,Dermatology, Rheumatology, Pediatrics, Infectious Diseases, Hematology and Transplant Unit) were simultaneously
tested for a suspect of either LTBI or active tuberculosis using all commercially available diagnostics: TST,QuantiFERON−TB
Gold (QFT−2G), QuantiFERON−TB Gold In−Tube(QFT−3G) and T−SPOT.TB(TS.TB).
Results. 42(18.3%),37(16.2%),59(25.8%) and 79(34.5%) patients were positive with TST,QFT−2G,QFT−3G and TS.TB,
respectively.TS.TB(p<0.001) and QFT−3G(p=0.016) provided more positive results than TST, while no difference was found for
TST and QFT−2G(p=0.53).All IGRA showed a good overall agreement (TS.TB vs QFT−2G,k=0.55; TS.TB vs
QFT−3G,k=0.72;QFT−2G vs QFT−3G, k=0.62). In 22 subjects (9.6%) QFT−3G was positive and QFT−2G negative.
Indeterminate results were more frequent with QFT−2G(18.3%) and QFT−3G (12.7%) than with TS.TB(1.3%,p<0.0001).
Conclusion. Rates of LTBI as detected by different diagnostic tests may have significant variations. Performances of various
IGRA formats were variable in this population
