title: Interferon-gamma release assays piloted as a latent tuberculous infection screening tool in Canadian federal inmates.
abstract: BACKGROUND
  Interferon-gamma release assays (IGRAs) may be useful in diagnosing latent tuberculous infection (LTBI) in inmates; however, published experience in these settings is limited.
  
  
  OBJECTIVE
  To identify variables associated with IGRA positivity among Canadian federal inmates with positive tuberculin skin test (TST) results.
  
  
  METHODS
  On intake, TST-positive (≥10 mm) inmates were offered an IGRA (QuantiFERON(®)-TB Gold), and demographic and historical data were collected. IGRA-positive and -negative inmates were compared using the χ(2) test and multivariable logistic regression; the final model's goodness of fit was assessed using Hosmer-Lemeshow test and area under the receiver operating characteristic curve (AUC).
  
  
  RESULTS
  Of 96 TST-positive inmates, 31 (32.3%) were IGRA-positive. Variables associated with positive IGRA were age >45 years (11/20 vs. 20/75, P = 0.016) and previous LTBI treatment (9/20 vs. 13/55, P = 0.032) in univariate analysis, and being from a country with a moderate or high estimated tuberculosis (TB) incidence (OR 3.5, 95%CI 1.3-9.4, P = 0.013) and absence of bacille Calmette-Guérin (BCG) vaccination (OR 3.3, 95%CI 1.2-9.0, P = 0.017) in multivariable analysis. The data fit the model well, classifying the group better than chance alone (AUC 0.67, P = 0.007).
  
  
  CONCLUSIONS
  High discordance with TST, particularly among BCG-vaccinated inmates and those from low TB incidence countries, suggest that IGRA may be useful in Canadian federal penitentiary screening programmes.
authors.affiliation: <label>*</label>Departments of Medical Microbiology & Infectious Diseases and Internal Medicine, University of Manitoba, Winnipeg, Manitoba.
authors.forename: I S
authors.initials: IS
authors.lastname: Schwartz
authors.affiliation: <label><sup>†</sup></label>Department of Internal Medicine, University of British Columbia, Vancouver, British Columbia.
authors.forename: P J
authors.initials: PJ
authors.lastname: Bach
authors.affiliation: <label><sup>‡</sup></label>Correctional Services Canada, Health Services, Kingston, Ontario.
authors.forename: B
authors.initials: B
authors.lastname: Roscoe
authors.affiliation: <label><sup>§</sup></label>Laboratory Services, Public Health Ontario, Kingston, Ontario.
authors.forename: A
authors.initials: A
authors.lastname: Majury
authors.affiliation: <label><sup>#</sup></label>Clinical Research Centre, Kingston General Hospital, Kingston, Ontario.
authors.forename: W M
authors.initials: WM
authors.lastname: Hopman
authors.affiliation: <label><sup>††</sup></label>Public Health Agency of Canada, Ottawa, Ontario.
authors.forename: E
authors.initials: E
authors.lastname: Ellis
authors.affiliation: <label><sup>‡</sup></label>Correctional Services Canada, Health Services, Kingston, Ontario.
authors.forename: T
authors.initials: T
authors.lastname: Garrahan
authors.affiliation: <label><sup>‡</sup></label>Correctional Services Canada, Health Services, Kingston, Ontario.
authors.forename: J
authors.initials: J
authors.lastname: Smith
authors.affiliation: <label><sup>‡</sup></label>Correctional Services Canada, Health Services, Kingston, Ontario.
authors.forename: R
authors.initials: R
authors.lastname: Barkley
authors.affiliation: <label><sup>‡</sup></label>Correctional Services Canada, Health Services, Kingston, Ontario.
authors.forename: L
authors.initials: L
authors.lastname: Panaro
authors.affiliation: <label><sup>§§</sup></label>Public Health Ontario, Laboratory Services, Toronto, Ontario.
authors.forename: F
authors.initials: F
authors.lastname: Jamieson
authors.affiliation: <label><sup>§</sup></label>Laboratory Services, Public Health Ontario, Kingston, Ontario.
authors.forename: C
authors.initials: C
authors.lastname: Froats
authors.affiliation: <label><sup>¶¶</sup></label>Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario.
authors.forename: I
authors.initials: I
authors.lastname: Gemmill
authors.affiliation: <label>**</label>Department of Public Health Sciences, Queen's University, Kingston, Ontario.
authors.forename: W L
authors.initials: WL
authors.lastname: Wobeser
mesh_terms: D000328:Adult; D001500:BCG Vaccine / Q000008:administration & dosage; D002170:Canada; D006801:Humans; D059425:Interferon-gamma Release Tests; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D015999:Multivariate Analysis; D010865:Pilot Projects; D011329:Prisoners / Q000706:statistics & numerical data*; D011330:Prisons; D014374:Tuberculin Test
chemical_list: D001500:BCG Vaccine