title: Performance of tests for latent tuberculosis in different groups of immunocompromised patients.
abstract: BACKGROUND
  Immunocompromised persons infected with Mycobacterium tuberculosis (MTB) have increased risk of tuberculosis (TB) reactivation, but their management is hampered by the occurrence of false-negative results of the tuberculin skin test (TST). The T-cell interferon (IFN)-gamma release blood assays T-SPOT.TB (TS.TB) [Oxford Immunotec; Abingdon, UK] and QuantiFERON-TB Gold In-Tube (QFT-IT) [Cellestis Ltd; Carnegie, VIC, Australia] might improve diagnostic accuracy for latent TB infection (LTBI) in high-risk persons, although their performance in different groups of immunocompromised patients is largely unknown.
  
  
  RESULTS
  Over a 1-year period, we prospectively enrolled patients in three different immunosuppressed groups, as follows: 120 liver transplantation candidates (LTCs); 116 chronically HIV-infected persons; and 95 patients with hematologic malignancies (HMs). TST, TS.TB, and QFT-IT were simultaneously performed, their results were compared, and intertest agreement was evaluated. Overall, TST provided fewer positive results (10.9%) than TS.TB (18.4%; p < 0.001) and QFT-IT (15.1%; p = 0.033). Significantly fewer HIV-infected individuals had at least one positive test (9.5%) compared with LTCs (35.8%; p < 0.001) and patients with HMs (29.5%; p < 0.001). Diagnostic agreement between tests was moderate (kappa = 0.40 to 0.65) and decreased in the HIV-infected group when the results of the TS.TB were compared with either TST (kappa = 0.16) or QFT-IT (kappa = 0.19). Indeterminate blood test results due to low positive control values were significantly more frequent with QFT-IT (7.2%) than with TS.TB (0.6%; p < 0.001).
  
  
  CONCLUSIONS
  Blood tests identified significantly more patients as being infected with MTB than TST, although diagnostic agreement varied across groups. Based on these results, we recommend tailoring application of the new blood IFN-gamma assays for LTBI in different high-risk groups and advise caution in their current use in immunosuppressed patients.
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy. Electronic address: luca.richeldi@unimore.it.
authors.forename: Luca
authors.initials: L
authors.lastname: Richeldi
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Losi
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: D'Amico
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Luppi
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Ferrari
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Mussini
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Codeluppi
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Cocchi
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Prati
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Paci
authors.affiliation: Policlinico Hospital, Modena, Italy.
authors.forename: Marisa
authors.initials: M
authors.lastname: Meacci
authors.affiliation: Policlinico Hospital, Modena, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Meccugni
authors.affiliation: Policlinico Hospital, Modena, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Rumpianesi
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Roversi
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Cerri
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Luppi
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Ferrara
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Latorre
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Giorgio E
authors.initials: GE
authors.lastname: Gerunda
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Torelli
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Esposito
authors.affiliation: University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Leonardo M
authors.initials: LM
authors.lastname: Fabbri