[Clinical performance of antigen-specific interferon-gamma assay for the diagnosis of latent tuberculosis in risky hospital-based populations].
OBJECTIVE
To evaluate the performance and the usefulness of an in vitro interferon gamma release assay in the diagnosis of latent tuberculosis infection in immunocompromised hospital-based population.


METHODS
A cohort of 445 high-risk adults from a hospital located in an intermediate tuberculosis burden area were prospectively evaluated for latent tuberculosis by means of the whole blood in vitro QuantiFERON-TB Gold assay (QTF), measuring tuberculosis-specific interferon gamma release by memory-effector T lymphocytes.


RESULTS
Overall the test displayed a positive result in 15.43% patients. Among the different risk groups, hemodialysis patients revealed the highest positive rates (30.23%). Indeterminate results (10.19% on the whole) were more often seen in neoplastic (18.03%) patients and in patients with autoimmune disease (17%). In 291 patients in whom QTF and Mantoux were simultaneously performed, concordance was moderate (kappa = 0.4520) with a 76.8% agreement when Mantoux was negative (179/233) but reaching only 50% (29/58) when Mantoux positive patients were selected.


CONCLUSIONS
QFT test is suitable for routine latent tuberculosis diagnosis in hospital-based immunocompromised patients. At least in some of them, i.e. hemodialysis and patients with autoimmune suppression, QFT adds valuable information for therapeutical decision-making. In Mantoux positive patients, it is very useful for ruling-out false positives due to BCG-vaccination and/or non-tuberculous mycobacterial infection.
Torres
Héctor E
HE
Servicio de Análisis Clínicos, Hospital de León, León, Spain.
Zapico
Marta
M
Vivas
Santiago
S
Mostaza
José L
JL
Blanco
Julio
J
Ruiz de Morales
José M G
JM
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016898:Interferon-alpha / Q000032:analysis* / Q000096:biosynthesis*; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012698:Serologic Tests / Q000379:methods; D014376:Tuberculosis / Q000175:diagnosis* / Q000276:immunology*
D016898:Interferon-alpha