title: T-SPOT.TB Interferon-γ Release Assay Performance in Healthcare Worker Screening at Nineteen U.S. Hospitals.
abstract: BACKGROUND
  Interferon-γ release assays have significant advantages over tuberculin skin testing in many clinical situations. However, recent studies have called into question their reliability in serial testing of healthcare workers because of reportedly high rates of positivity and high conversion/reversion rates on retesting.
  
  
  OBJECTIVE
  To define the performance characteristics of the T-SPOT.TB test, an interferon-γ release assay, during serial screening programs of healthcare workers at 19 U.S. hospitals.
  
  
  METHODS
  A total of 42,155 T-SPOT.TB test results from healthcare workers at 19 geographically diverse hospitals obtained for routine tuberculosis screening programs were analyzed to determine the rates of positivity, reversion, and conversion in serial testing data.
  
  
  RESULTS
  In 19,630 evaluable serial pairs from 16,076 healthcare workers, the mean test positivity rate was 2.3% (range, 0.0-27.4%). The mean conversion rate was 0.8% (range, 0.0-2.5%), and the mean reversion rate was 17.6%. Positivity and conversion rates correlated with known tuberculosis risk factors including age and sex. The observed specificity of the T-SPOT.TB test was at least 98.6%.
  
  
  CONCLUSIONS
  The high concordance and test completion rates in this study suggest that the T-SPOT.TB test is a reliable tool for healthcare worker serial screening. As expected, the observed positivity rates were lower compared with the tuberculin skin test, likely reflecting the higher specificity of this test. Furthermore, the observed rates of conversion were low and significantly correlated with the geographic incidence of tuberculosis. Our findings suggest that the T-SPOT.TB test is an accurate and reliable way to screen healthcare workers.
authors.affiliation: 1 Department of Pathology and Laboratory Medicine, St. Vincent Hospital, Worcester, Massachusetts.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: King
authors.affiliation: 2 Occupational Health Services, Detroit Medical Center, Detroit, Michigan.
authors.forename: Mark
authors.initials: M
authors.lastname: Upfal
authors.affiliation: 3 Occupational Health Services, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Andrew
authors.initials: A
authors.lastname: Gottlieb
authors.affiliation: 4 Department of Medicine, Employee Health Services and Occupational Injury Care and Wellness, UMass Memorial Health Care, Worcester, Massachusetts.
authors.forename: Philip
authors.initials: P
authors.lastname: Adamo
authors.affiliation: 5 Division of Occupational Medicine, Johns Hopkins University, School of Medicine, Baltimore, Maryland.
authors.forename: Edward
authors.initials: E
authors.lastname: Bernacki
authors.affiliation: 6 Occupational Health Services, St. David's Medical Center, Austin, Texas.
authors.forename: Chris P
authors.initials: CP
authors.lastname: Kadlecek
authors.affiliation: 7 Occupational Medicine, St. Francis Hospital, Indianapolis, Indiana.
authors.forename: Jeffrey G
authors.initials: JG
authors.lastname: Jones
authors.affiliation: 8 Health, Safety and Environment, Johns Hopkins Health System and University, Baltimore, Maryland.
authors.forename: Frances
authors.initials: F
authors.lastname: Humphrey-Carothers
authors.affiliation: 3 Occupational Health Services, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Albert F
authors.initials: AF
authors.lastname: Rielly
authors.affiliation: 9 Employee Health, Medical City Hospital, Dallas, Texas.
authors.forename: Pamela
authors.initials: P
authors.lastname: Drewry
authors.affiliation: 10 Risk Management/Occupational Health, Sonora Regional Medical Center, Sonora, California.
authors.forename: Kathy
authors.initials: K
authors.lastname: Murray
authors.affiliation: 11 Employee Health, Baptist Health Louisville, Louisville, Kentucky.
authors.forename: Marcie
authors.initials: M
authors.lastname: DeWitt
authors.affiliation: 12 Oxford Immunotec, Marlborough, Massachusetts; and.
authors.forename: Janet
authors.initials: J
authors.lastname: Matsubara
authors.affiliation: 12 Oxford Immunotec, Marlborough, Massachusetts; and.
authors.forename: Louis
authors.initials: L
authors.lastname: O'Dea
authors.affiliation: 13 Veristat LLC, Holliston, Massachusetts.
authors.forename: John
authors.initials: J
authors.lastname: Balser
authors.affiliation: 12 Oxford Immunotec, Marlborough, Massachusetts; and.
authors.forename: Peter
authors.initials: P
authors.lastname: Wrighton-Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006761:Hospitals; D006801:Humans; D059425:Interferon-gamma Release Tests / Q000706:statistics & numerical data*; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D010564:Personnel, Hospital / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D014374:Tuberculin Test / Q000706:statistics & numerical data; D014376:Tuberculosis / Q000175:diagnosis*; D014481:United States; D055815:Young Adult
keywords: LTBI; conversion; reversion; serial testing; tuberculosis screening