title: Interferon-Gamma Release Assays and Pediatric Public Health Tuberculosis Screening: The San Francisco Program Experience 2005 to 2008.
abstract: BACKGROUND
  Interferon-gamma release assay utilization in pediatric tuberculosis (TB) screening is limited by a paucity of longitudinal experience, particularly in low-TB burden populations.
  
  
  METHODS
  We conducted a retrospective review of QuantiFERON (QFT)-TB Gold results in San Francisco children from 2005 to 2008. Concordance with the tuberculin skin test (TST) was analyzed for a subset of children. Progression to active disease was determined through San Francisco and California TB registry matches.
  
  
  RESULTS
  Of 1092 children <15 years of age, 853 (78%) were foreign-born, and 136 (12%) were exposed to active TB cases (contacts). QuantiFERON tests were positive in 72 of 1092 (7%) children; 15 of 136 (11%) recent contacts; 53 of 807 (7%) foreign-born noncontacts; and 4 of 149 (3%) US-born noncontacts. QuantiFERON-negative/TST-positive discordance was seen more often in foreign-born/bacille Calmette-Guerin (BCG)-vaccinated children <5 years of age (52 of 56, 93%) compared to those ≥ 5 years of age (90 of 123, 73%; P = .003). Foreign-born, BCG-vaccinated children were more than twice as likely to have a discordant (79%) result as US-born, non-BCG-vaccinated children (37%; P < .0001). During 5587 person-years of follow-up of untreated children, including 146 TST-positive/QFT-negative children, no cases of active TB were identified, consistent with a negative predictive value of 100%.
  
  
  CONCLUSIONS
  Our experience supports the use of QFT to evaluate latent TB infection in children, particularly young BCG-vaccinated children. The proportion of QFT-positive results correlated with risk of exposure, and none of the untreated QFT-negative children developed TB. The low QFT-positive rate highlights the need for more selective testing based on current epidemiology and TB exposure risk.
authors.affiliation: San Francisco Department of Public Health, Population Health Division, California.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Grinsdale
authors.affiliation: Division of Infectious Diseases, Children's Hospital and Research Center Oakland, California.
authors.forename: Shamim
authors.initials: S
authors.lastname: Islam
authors.affiliation: Pangaea Global AIDS Foundation, Oakland, California.
authors.forename: Olivia Chang
authors.initials: OC
authors.lastname: Tran
authors.affiliation: Centers for Disease Control and Prevention, Division of Tuberculosis Elimination, Field Services Branch, Atlanta, Georgia.
authors.forename: Christine S
authors.initials: CS
authors.lastname: Ho
authors.affiliation: San Francisco Department of Public Health, Population Health Division, California Qiagen, Valencia, California.
authors.forename: L Masae
authors.initials: LM
authors.lastname: Kawamura
authors.affiliation: San Francisco Department of Public Health, Population Health Division, California.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Higashi
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D059425:Interferon-gamma Release Tests; D008297:Male; D008403:Mass Screening; D012189:Retrospective Studies; D012495:San Francisco / Q000453:epidemiology; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology
keywords: interferon-gamma release assays; pediatrics; tuberculosis