title: Tuberculosis progression rates in U.S. Immigrants following screening with interferon-gamma release assays.
abstract: Interferon-gamma release assays may be used as an alternative to the tuberculin skin test for detection of M. tuberculosis infection. However, the risk of active tuberculosis disease following screening using interferon-gamma release assays in immigrants is not well defined. To address these uncertainties, we determined the incidence rates of active tuberculosis disease in a cohort of high-risk immigrants with Class B TB screened with interferon-gamma release assays (IGRAs) upon arrival in the United States.
  
  
  
  Using a retrospective cohort design, we enrolled recent U.S. immigrants with Class B TB who were screened with an IGRA (QuantiFERON ® Gold or Gold In-Tube Assay) at the San Francisco Department of Public Health Tuberculosis Control Clinic from January 2005 through December 2010. We reviewed records from the Tuberculosis Control Patient Management Database and from the California Department of Public Health Tuberculosis Case Registry to determine incident cases of active tuberculosis disease through February 2015.
  
  
  
  Of 1233 eligible immigrants with IGRA screening at baseline, 81 (6.6 %) were diagnosed with active tuberculosis disease as a result of their initial evaluation. Of the remaining 1152 participants without active tuberculosis disease at baseline, 513 tested IGRA-positive and 639 tested IGRA-negative. Seven participants developed incident active tuberculosis disease over 7730 person-years of follow-up, for an incidence rate of 91 per 100,000 person-years (95 % CI 43-190). Five IGRA-positive and two IGRA-negative participants developed active tuberculosis disease (incidence rates 139 per 100,000 person-years (95 % CI 58-335) and 48 per 100,000 person-years (95 % CI 12-193), respectively) for an unadjusted incidence rate ratio of 2.9 (95 % CI 0.5-30, p = 0.21). IGRA test results had a negative predictive value of 99.7 % but a positive predictive value of only 0.97 %.
  
  
  
  Among high-risk immigrants without active tuberculosis disease at the time of entry into the United States, risk of progression to active tuberculosis disease was higher in IGRA-positive participants compared with IGRA-negative participants. However, these findings did not reach statistical significance, and a positive IGRA at enrollment had a poor predictive value for progressing to active tuberculosis disease. Additional research is needed to identify biomarkers and develop clinical algorithms that can better predict progression to active tuberculosis disease among U.S. immigrants.
authors: Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California San Francisco, San Francisco, CA, USA. Robert.Blount@ucsf.edu.|Division of Pediatric Pulmonary Medicine, University of California, San Francisco, CA, USA. Robert.Blount@ucsf.edu.
authors: Robert J
authors: RJ
authors: Blount
authors: Department of Internal Medicine, University of California, Davis, Sacramento, CA, USA. minhchi.tran@gmail.com.
authors: Minh-Chi
authors: MC
authors: Tran
authors: Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California San Francisco, San Francisco, CA, USA.
authors: Charles K
authors: CK
authors: Everett
authors: Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California San Francisco, San Francisco, CA, USA.
authors: Adithya
authors: A
authors: Cattamanchi
authors: Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California San Francisco, San Francisco, CA, USA.
authors: John Z
authors: JZ
authors: Metcalfe
authors: Department of Medicine, University of California, San Francisco, CA, USA.
authors: Denise
authors: D
authors: Connor
authors: Department of Medicine, University of California, San Francisco, CA, USA.
authors: Cecily R
authors: CR
authors: Miller
authors: San Francisco Department of Public Health, Population Health Division, Office of Equity and Quality Improvement, San Francisco, CA, USA.
authors: Jennifer
authors: J
authors: Grinsdale
authors: San Francisco Department of Public Health, Population Health Division, Disease Prevention and Control Branch, San Francisco, CA, USA.
authors: Julie
authors: J
authors: Higashi
authors: Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California San Francisco, San Francisco, CA, USA.
authors: Payam
authors: P
authors: Nahid
mesh_terms: D015415:Biomarkers / Q000097:blood; D002140:California; D018450:Disease Progression; D054242:Emigrants and Immigrants / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D059425:Interferon-gamma Release Tests; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D012189:Retrospective Studies; D012495:San Francisco; D014374:Tuberculin Test / Q000379:methods; D014376:Tuberculosis / Q000175:diagnosis
chemical_list: D015415:Biomarkers
keywords: Active tuberculosis disease; Chest x-ray (CXR); Foreign-born; Immigrant; Incidence rate; Interferon-gamma release assay (IGRA); Latent tuberculosis infection (LTBI); Preventive chemotherapy; Tuberculosis (TB)