title: Role of confirmatory interferon-gamma release assays in school outbreaks of tuberculosis in South Korea.
abstract: OBJECTIVE
  To investigate the usefulness of confirmatory QuantiFERON(®) (QFT) testing among tuberculin skin test (TST) positive contacts to diagnose latent tuberculous infection (LTBI) in tuberculosis (TB) outbreaks among adolescents.
  
  
  METHODS
  We used the Korean national claims database to identify the development of active TB disease in relation to initial TST (cut-off 10 mm induration) and subsequent QFT results.
  
  
  RESULTS
  A total of 7475 contacts in 89 schools were divided into four groups: TST- (n = 5714), TST+/QFT+ (n = 534), TST+/QFT- (n = 697) and TST+ only (n = 530). The mean duration of follow-up was 3.9 ± 0.9 years. For contacts with no LTBI treatment (n = 6868), TB incidence rates per 1000 person-years (py) and the adjusted hazard ratio (HR) compared with TST- individuals were as follows: TST+/QFT+, 66.2/1000 py (HR 35.59, 95%CI 14.03-90.31, P < 0.001); TST+ only, 10.1/1000 py (HR 5.16, 95%CI 2.91-9.17, P < 0.001); TST+/QFT-, 4.0/1000 py (HR 2.05, 95%CI 1.05-4.01, P = 0.035); and TST- 2.0/1000 py. The TB progression rate was significantly higher in TST+/QFT+ than in TST+/QFT- individuals (HR 16.82, 95 CI 5.84-48.46, P < 0.001).
  
  
  CONCLUSIONS
  A confirmatory QFT for TST+ contacts could reduce the number of candidates for LTBI treatment after school TB outbreaks.
authors: Korean Institute of Tuberculosis, Osong, Republic of Korea.
authors: H J
authors: HJ
authors: Kim
authors: Korean Institute of Tuberculosis, Osong, Republic of Korea.
authors: G-H
authors: GH
authors: Lee
authors: Korean Institute of Tuberculosis, Osong, Republic of Korea.
authors: S
authors: S
authors: Ryoo
authors: Korean Institute of Tuberculosis, Osong, Republic of Korea.
authors: S-Y
authors: SY
authors: Oh
authors: Korean Institute of Tuberculosis, Osong, Republic of Korea.
authors: J-B
authors: JB
authors: Lee
authors: Division of Pulmonary, Sleep and Critical Care Medicine, Department of Internal Medicine, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Republic of Korea.
authors: J H
authors: JH
authors: Kim
authors: Division of Pulmonary, Sleep and Critical Care Medicine, Department of Internal Medicine, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Republic of Korea.
authors: C
authors: C
authors: Shin
authors: Division of Pulmonary, Sleep and Critical Care Medicine, Department of Internal Medicine, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Republic of Korea.
authors: S H
authors: SH
authors: Lee
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D002648:Child; D016001:Confidence Intervals; D016358:Contact Tracing / Q000379:methods; D016208:Databases, Factual; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D059425:Interferon-gamma Release Tests / Q000379:methods*; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology*; D008297:Male; D016016:Proportional Hazards Models; D056910:Republic of Korea / Q000453:epidemiology; D012380:Role; D012572:School Health Services; D017678:Sex Distribution; D013334:Students / Q000706:statistics & numerical data; D014374:Tuberculin Test / Q000379:methods; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000453:epidemiology*; D055815:Young Adult