title: Contribution of interferon-γ release assays (IGRAs) to the diagnosis of latent tuberculosis infection after renal transplantation.
abstract: BACKGROUND
  Renal transplant recipients (RTRs), as all immunosuppressed patients, are at increased risk of reactivating latent tuberculosis infection (LTBI). Detecting LTBI in this population is therefore important to prevent active TB. The tuberculin skin test (TST) has a poor sensitivity in this setting.
  
  
  METHODS
  The aim of this prospective study was to compare the diagnostic performance of the TST and two interferon-γ release assays (IGRAs): T-SPOT.TB (Oxford Immunotec, Oxford, UK) and QuantiFERON Gold In-Tube (QGIT; Cellestis, Australia), performed simultaneously, for the detection of patients with risk factors for LTBI or a definite history of TB among RTRs under stable immunosuppression.
  
  
  RESULTS
  Two hundred five patients (ages 59±13 years, tested 10.4±7.1 years after transplantation) were studied. Positivity rate was 4.5% for TST, 20.5% for T-SPOT.TB, and 23.5% for QGIT. Agreement between IGRAs was fair (κ=0.71). Sensitivity of T-SPOT.TB and QGIT for detection of prior active TB was 55.6% (95% confidence interval [CI], 21.2-86.3) and 44.4 (95% CI, 13.7-78.8), respectively. Sensitivity of both IGRAs for detection of risk factors for LTBI was 33.3% (95% CI, 19.6-49.5). Specificity was 85.5% (95% CI, 78.9-90.7) for T-SPOT.TB and 80.1% (95% CI, 72.9-86.2) for QGIT. Combining IGRAs did not significantly improve sensitivity.
  
  
  CONCLUSIONS
  Because their sensitivity for detecting prior active TB and probable LTBI in RTRs is very low, IGRAs cannot be used to exclude LTBI. These results emphasize the limitations of IGRAs in the setting of chronic immunosuppressive therapy.
authors.affiliation: Division of Nephrology, Geneva University Hospitals, Geneva, Switzerland. Karine.Hadaya@hcuge.ch
authors.forename: Karine
authors.initials: K
authors.lastname: Hadaya
authors.forename: Pierre-Olivier
authors.initials: PO
authors.lastname: Bridevaux
authors.forename: Pascale
authors.initials: P
authors.lastname: Roux-Lombard
authors.forename: Armelle
authors.initials: A
authors.lastname: Delort
authors.forename: Patrick
authors.initials: P
authors.lastname: Saudan
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Martin
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Janssens
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000009:adverse effects / Q000627:therapeutic use; D007371:Interferon-gamma / Q000097:blood*; D059425:Interferon-gamma Release Tests / Q000379:methods*; D007676:Kidney Failure, Chronic / Q000150:complications / Q000601:surgery*; D016030:Kidney Transplantation / Q000009:adverse effects*; D055985:Latent Tuberculosis / Q000097:blood / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014374:Tuberculin Test / Q000379:methods*
chemical_list: D007166:Immunosuppressive Agents; D007371:Interferon-gamma