I S Schwartz1, P J Bach2, B Roscoe3, A Majury4, W M Hopman5, E Ellis6, T Garrahan3, J Smith3, R Barkley3, L Panaro3, F Jamieson7, C Froats4, I Gemmill8, W L Wobeser9. 1. <label>*</label>Departments of Medical Microbiology & Infectious Diseases and Internal Medicine, University of Manitoba, Winnipeg, Manitoba. 2. <label><sup>†</sup></label>Department of Internal Medicine, University of British Columbia, Vancouver, British Columbia. 3. <label><sup>‡</sup></label>Correctional Services Canada, Health Services, Kingston, Ontario. 4. <label><sup>§</sup></label>Laboratory Services, Public Health Ontario, Kingston, Ontario. 5. <label><sup>#</sup></label>Clinical Research Centre, Kingston General Hospital, Kingston, Ontario. 6. <label><sup>††</sup></label>Public Health Agency of Canada, Ottawa, Ontario. 7. <label><sup>§§</sup></label>Public Health Ontario, Laboratory Services, Toronto, Ontario. 8. <label><sup>¶¶</sup></label>Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario. 9. <label>**</label>Department of Public Health Sciences, Queen's University, Kingston, Ontario.
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. DESIGN: 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). CONCLUSION: 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.
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. DESIGN: 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). CONCLUSION: 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: Edward C Jones-López; Laura F White; Bruce Kirenga; Francis Mumbowa; Martin Ssebidandi; Stephanie Moine; Olive Mbabazi; Gerald Mboowa; Irene Ayakaka; Soyeon Kim; Christina S Thornton; Alphonse Okwera; Moses Joloba; Kevin P Fennelly Journal: PLoS One Date: 2015-09-22 Impact factor: 3.240