title: Routine hospital use of a new commercial whole blood interferon-gamma assay for the diagnosis of tuberculosis infection.
abstract: BACKGROUND
  Interferon (IFN)-gamma blood tests may improve the current level of diagnostic accuracy for tuberculosis infection. The QuantiFERON-TB Gold (QFT-Gold) has been used in selected populations and shows higher specificity than the tuberculin skin test (TST).
  
  
  OBJECTIVE
  To evaluate the QFT-Gold test in unselected patients and assess the level of agreement with the TST.
  
  
  METHODS
  The test has been routinely performed on whole blood samples in our microbiology laboratory for 8 months. Demographic, clinical, and microbiological data have been collected and correlated to the QFT-Gold results.
  
  
  RESULTS
  Of 318 patients tested, 68 (21.4%) gave an indeterminate (low positive mitogen control) QFT-Gold result. Indeterminate results were significantly overrepresented in patients with a negative TST (28.9% vs. 6.6% in TST-positive patients; p < 0.0001, chi2 test) and were more frequent in patients receiving immunosuppressive therapies than in those who were not receiving such treatments (odds ratio, 3.35; 95% confidence interval, 1.84-6.08; p < 0.0001). After excluding indeterminate results, the concordance between QFT-Gold and TST was significantly lower in Bacille Calmette-Guérin-vaccinated individuals (41.5%) than in nonvaccinated individuals (80.3%) (p < 0.0001). In 11 patients with active tuberculosis (5 culture-confirmed), QFT-Gold provided more positive results than the TST (66.7% vs. 33.3%; p = 0.165).
  
  
  CONCLUSIONS
  The QFT-Gold test is feasible in routine hospital use for the diagnosis of tuberculosis infection. As with the TST, immunosuppression may negatively affect the test's performance, with a significant rate of indeterminate results in the most vulnerable population.
authors.affiliation: Section of Respiratory Disease, Department of Oncology, Haematology and Respiratory Disease, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Ferrara
authors.forename: Monica
authors.initials: M
authors.lastname: Losi
authors.forename: Marisa
authors.initials: M
authors.lastname: Meacci
authors.forename: Barbara
authors.initials: B
authors.lastname: Meccugni
authors.forename: Roberto
authors.initials: R
authors.lastname: Piro
authors.forename: Pietro
authors.initials: P
authors.lastname: Roversi
authors.forename: Barbara Maria
authors.initials: BM
authors.lastname: Bergamini
authors.forename: Roberto
authors.initials: R
authors.lastname: D'Amico
authors.forename: Patrizia
authors.initials: P
authors.lastname: Marchegiano
authors.forename: Fabio
authors.initials: F
authors.lastname: Rumpianesi
authors.forename: Leonardo M
authors.initials: LM
authors.lastname: Fabbri
authors.forename: Luca
authors.initials: L
authors.lastname: Richeldi
mesh_terms: D000328:Adult; D000368:Aged; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007371:Interferon-gamma / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012882:Skin Tests; D014376:Tuberculosis / Q000175:diagnosis*
chemical_list: D007371:Interferon-gamma