title: Comparison of TST and IGRA in Diagnosis of Latent Tuberculosis Infection in a High TB-Burden Setting.
abstract: BACKGROUND
  There are currently two tests for diagnosing latent tuberculosis infection (LTBI); TST and IGRA. However, it is still unclear that which one of these tests performs better in high TB-burden settings.
  
  
  METHODS
  1511 household contacts of pulmonary TB patients were enrolled to compare the performance of TST and IGRA for LTBI. At baseline all participant underwent testing for IGRA [QuantiFERON-TB® Gold In-tube (QFT-GIT) assay] and TST [2 tuberculin unit (TU), purified protein derivative (PPD), RT23, Staten Serum Institute (SSI), Copenhagen, Denmark]. All the household contacts were followed-up for two years for incident TB cases.
  
  
  RESULTS
  Active TB was diagnosed in 76 household contacts at an incidence rate of 2.14 per 1000 person-years. Both, TST [Hazard Ratio (HR): 1.14, 95% confidence interval (CI): 0.72-1.79, p = 0.57], as well as QFT-GIT assay (HR: 1.66, 95% CI: 0.97-2.84, p = 0.06) results at baseline were not significantly associated with subsequent development of active TB among household contacts of pulmonary TB patients.
  
  
  CONCLUSIONS
  Neither TST nor IGRA predicted subsequent development of active TB among household contacts of pulmonary TB patients during follow-up. However, keeping in view the cost, and other logistics, TST remains the most preferred method for LTBI diagnosis in resource-limited, high TB-burden settings.
authors.affiliation: Department of Internal Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Surendra K
authors.initials: SK
authors.lastname: Sharma
authors.affiliation: Department of Internal Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Richa
authors.initials: R
authors.lastname: Vashishtha
authors.affiliation: National Center for Disease Control (NCDC)2, New Delhi, India.
authors.forename: L S
authors.initials: LS
authors.lastname: Chauhan
authors.affiliation: Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: V
authors.initials: V
authors.lastname: Sreenivas
authors.affiliation: Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Divya
authors.initials: D
authors.lastname: Seth
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005191:Family Characteristics; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D059425:Interferon-gamma Release Tests / Q000379:methods; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000382:microbiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis; D010641:Phenotype; D012307:Risk Factors; D014374:Tuberculin Test / Q000379:methods; D014376:Tuberculosis / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D055815:Young Adult