title: Interferon-gamma release assays and tuberculin skin testing for diagnosing latent Mycobacterium tuberculosis infection in at-risk groups in Poland.
abstract: OBJECTIVE
  The diagnostics of latent tuberculosis infection in Poland using the tuberculin skin test is challenging due to the obligatory Bacillus Calmette-Guérin vaccinations. Interferon-gamma release assays are still very rarely used for diagnostics. We compared the tuberculin skin test and the QuantiFERON-TB Gold In-Tube test to evaluate the degree of latent tuberculosis infection in at-risk groups for tuberculosis (homeless, close contacts, periodic contacts, nursing-home attendees) and in healthy individuals.
  
  
  METHODS
  QuantiFERON-TB Gold In-Tube tests were carried out on 785 individuals from the homeless (n=150), close contacts (n=171), periodic contacts (n=163), nursing-home attendees (n=152), and healthy individuals (n=149). The tuberculin skin test was performed on 129, 156, 147, 148, and 121 participants, respectively. We evaluated the (a) correlation between serum concentrations of interferon gamma and the tuberculin-skin-test induration diameter; (b) between the number of QuantiFERON-TB Gold In-Tube-positive results and the tuberculin-skin-test diameter in the studied groups; and (c) agreement between both tests and the kappa coefficient using the tuberculin-skin-test diameters of 5, 10, and 15mm.
  
  
  RESULTS
  Larger tuberculin-skin-test induration diameters were associated with elevated serum concentrations of interferon gamma. We found a positive correlation between the number of positive QuantiFERON-TB Gold In-Tube screening results and the tuberculin-skin-test induration diameter. The agreement between QuantiFERON-TB Gold In-Tube and tuberculin-skin-test screening results improved with increasing tuberculin-skin-test induration diameter.
  
  
  CONCLUSIONS
  Based on measures of tuberculin-skin-test induration diameter alone, it is difficult to diagnose latent tuberculosis infection with certainty. The agreement of the QuantiFERON-TB Gold In-Tube test increases with the tuberculin-skin-test diameter. Tuberculin-skin-test diameters larger than 15mm are more likely to be associated with active infection.
authors.affiliation: Department of Pulmonology, Jagiellonian University Medical College, Skawinska 8, 31-066 Kraków, Poland. Electronic address: krucza@gmail.com.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kruczak
authors.affiliation: Department of Pulmonology, Jagiellonian University Medical College, Skawinska 8, 31-066 Kraków, Poland.
authors.forename: Lucyna
authors.initials: L
authors.lastname: Mastalerz
authors.affiliation: Department of Pulmonology, Jagiellonian University Medical College, Skawinska 8, 31-066 Kraków, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Sładek
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006703:Ill-Housed Persons; D006801:Humans; D007371:Interferon-gamma / Q000097:blood; D059425:Interferon-gamma Release Tests; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011044:Poland; D012307:Risk Factors; D014374:Tuberculin Test; D055815:Young Adult
chemical_list: D007371:Interferon-gamma
keywords: Latent tuberculosis infection; QuantiFERON-GIT; Tuberculin skin test; Tuberculosis