title: Impact of targeted testing for latent tuberculosis infection using commercially available diagnostics.
abstract: BACKGROUND
  The interferon-γ release assays (IGRAs) are increasingly being used as an alternative to the tuberculin skin test (TST). Although IGRAs may have better specificity and certain logistic advantages to the TST, their use may contribute to overtesting of low-prevalence populations if testing is not targeted. The objective of this study was to evaluate the accuracy of a risk factor questionnaire in predicting a positive test result for latent tuberculosis infection using the 3 commercially available diagnostics.
  
  
  METHODS
  A cross-sectional comparison study was performed among recruits undergoing Army basic training at Fort Jackson, South Carolina, from April through June 2009. The tests performed included: (1) a risk factor questionnaire; (2) the QuantiFERON Gold In-Tube test (Cellestis Limited, Carnegie, Victoria, Australia); (3) the T-SPOT.TB test (Oxford Immunotec Limited, Abingdon, United Kingdom); and (4) the TST (Sanofi Pasteur Ltd., Toronto, Ontario, Canada). Prediction models used logistic regression to identify factors associated with positive test results. RFQ prediction models were developed independently for each test.
  
  
  RESULTS
  Use of a 4-variable model resulted in 79% sensitivity, 92% specificity, and a c statistic of 0.871 in predicting a positive TST result. Targeted testing using these risk factors would reduce testing by >90%. Models predicting IGRA outcomes had similar specificities as the skin test but had lower sensitivities and c statistics.
  
  
  CONCLUSIONS
  As with the TST, testing with IGRAs will result in false-positive results if the IGRAs are used in low-prevalence populations. Regardless of the test used, targeted testing is critical in reducing unnecessary testing and treatment.
  
  
  BACKGROUND
  NCT00804713.
authors.affiliation: Division of Preventive Medicine, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA. james.mancuso@us.army.mil
authors.forename: James D
authors.initials: JD
authors.lastname: Mancuso
authors.forename: David
authors.initials: D
authors.lastname: Tribble
authors.forename: Gerald H
authors.initials: GH
authors.lastname: Mazurek
authors.forename: Yuanzhang
authors.initials: Y
authors.lastname: Li
authors.forename: Cara
authors.initials: C
authors.lastname: Olsen
authors.forename: Naomi E
authors.initials: NE
authors.lastname: Aronson
authors.forename: Lawrence
authors.initials: L
authors.lastname: Geiter
authors.forename: Donald
authors.initials: D
authors.lastname: Goodwin
authors.forename: Lisa W
authors.initials: LW
authors.lastname: Keep
mesh_terms: D000293:Adolescent; D000328:Adult; D019411:Clinical Laboratory Techniques / Q000379:methods*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D055985:Latent Tuberculosis / Q000175:diagnosis*; D008297:Male; D011237:Predictive Value of Tests; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity; D013022:South Carolina; D011795:Surveys and Questionnaires; D055815:Young Adult