title: Performance of commercial blood tests for the diagnosis of latent tuberculosis infection in children and adolescents.
abstract: BACKGROUND
  The accurate diagnosis of latent tuberculosis infection reduces the risk of progression to severe disseminated disease. However, in young children, a major limitation of the standard tuberculin skin test is that false-negative results cannot be detected. The new interferon-gamma release assays QuantiFERON-TB Gold (Cellestis Carnegie Victoria, Australia), QuantiFERON-TB In-Tube (Cellestis), and T-SPOT.TB (Oxford Immunotec, Abingdon, United Kingdom) show promise of greater accuracy, but they may also be affected by impaired cellular immunity, resulting in indeterminate results (ie, insufficient response in positive-control wells).
  
  
  OBJECTIVE
  To evaluate the impact of age on the performance of interferon-gamma release assays when used in a routine hospital setting among children tested for suspected active or latent TB infection.
  
  
  METHODS
  We retrospectively studied 496 children 0 to 19 years of age who had been tested with the tuberculin skin test and at least 1 interferon-gamma release assay: 181 with QuantiFERON-TB Gold and 315 with QuantiFERON-TB In-Tube. In 154 of the children, paired interferon-gamma release assay testing was available: 87 with QuantiFERON-TB Gold/T-SPOT.TB and 67 with QuantiFERON-TB In-Tube/T-SPOT.TB.
  
  
  RESULTS
  Compared with T-SPOT.TB, the rates of indeterminate results were significantly higher for both QuantiFERON-TB Gold and QuantiFERON-TB In-Tube. QuantiFERON-TB Gold and QuantiFERON-TB In-Tube also gave indeterminate results more frequently in children <4 years of age than in those >/=4 years of age. Indeterminate results were associated with younger age for both QuantiFERON-TB Gold and QuantiFERON-TB In-Tube but not for T-SPOT.TB. Considering age as a binary variable (<4 and >/=4 years of age), a significantly higher concentration of phytohaemagglutinin-produced interferon-gamma was observed in older children with both QuantiFERON-TB Gold and QuantiFERON-TB In-Tube.
  
  
  CONCLUSIONS
  Different blood tests for the diagnosis of latent tuberculosis infection in children seem to perform differently, because both QuantiFERON-TB tests were more likely than T-SPOT.TB to give indeterminate results in children <4 years of age.
authors.affiliation: University of Modena and Reggio Emilia, Department of Respiratory Diseases, Policlinico Hospital of Modena, Via del Pozzo 71, 41100 Modena, Italy.
authors.forename: Barbara Maria
authors.initials: BM
authors.lastname: Bergamini
authors.forename: Monica
authors.initials: M
authors.lastname: Losi
authors.forename: Francesca
authors.initials: F
authors.lastname: Vaienti
authors.forename: Roberto
authors.initials: R
authors.lastname: D'Amico
authors.forename: Barbara
authors.initials: B
authors.lastname: Meccugni
authors.forename: Marisa
authors.initials: M
authors.lastname: Meacci
authors.forename: Donatella
authors.initials: D
authors.lastname: De Giovanni
authors.forename: Fabio
authors.initials: F
authors.lastname: Rumpianesi
authors.forename: Leonardo M
authors.initials: LM
authors.lastname: Fabbri
authors.forename: Fiorella
authors.initials: F
authors.lastname: Balli
authors.forename: Luca
authors.initials: L
authors.lastname: Richeldi
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006403:Hematologic Tests / Q000379:methods*; D006801:Humans; D007223:Infant; D007371:Interferon-gamma / Q000097:blood*; D007558:Italy; D008297:Male; D008403:Mass Screening; D009169:Mycobacterium tuberculosis / Q000276:immunology; D011237:Predictive Value of Tests; D011933:Reagent Kits, Diagnostic; D012189:Retrospective Studies; D012306:Risk; D014374:Tuberculin Test / Q000706:statistics & numerical data; D014388:Tuberculosis, Lymph Node / Q000175:diagnosis* / Q000453:epidemiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000453:epidemiology
chemical_list: D011933:Reagent Kits, Diagnostic; D007371:Interferon-gamma