title: Performance of the tuberculin skin test and interferon-gamma release assay for detection of tuberculosis infection in immunocompromised patients in a BCG-vaccinated population.
abstract: BACKGROUND
  Interferon-gamma release assay (IGRA) may improve diagnostic accuracy for latent tuberculosis infection (LTBI). This study compared the performance of the tuberculin skin test (TST) with that of IGRA for the diagnosis of LTBI in immunocompromised patients in an intermediate TB burden country where BCG vaccination is mandatory.
  
  
  METHODS
  We conducted a retrospective observational study of patients given the TST and an IGRA, the QuantiFERON-TB Gold In-Tube (QFT-IT), at Severance Hospital, a tertiary hospital in South Korea, from December 2006 to May 2009.
  
  
  RESULTS
  Of 211 patients who underwent TST and QFT-IT testing, 117 (55%) were classified as immunocompromised. Significantly fewer immunocompromised than immunocompetent patients had positive TST results (10.3% vs. 27.7%, p 0.001), whereas the percentage of positive QFT-IT results was comparable for both groups (21.4% vs. 25.5%). However, indeterminate QFT-IT results were more frequent in immunocompromised than immunocompetent patients (21.4% vs. 9.6%, p 0.021). Agreement between the TST and QFT-IT was fair for the immunocompromised group (kappa = 0.38), but moderate agreement was observed for the immunocompetent group (kappa = 0.57). Indeterminate QFT-IT results were associated with anaemia, lymphocytopenia, hypoproteinemia, and hypoalbuminemia.
  
  
  CONCLUSIONS
  In immunocompromised patients, the QFT-IT may be more sensitive than the TST for detection of LTBI, but it resulted in a considerable proportion of indeterminate results. Therefore, both tests may maximise the efficacy of screening for LTBI in immunocompromised patients.
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul, Republic of Korea. NARAE97@yuhs.ac
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Kim
authors.forename: Ju Eun
authors.initials: JE
authors.lastname: Lim
authors.forename: Ji Ye
authors.initials: JY
authors.lastname: Jung
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Son
authors.forename: Kyung Jong
authors.initials: KJ
authors.lastname: Lee
authors.forename: Yoe Wun
authors.initials: YW
authors.lastname: Yoon
authors.forename: Byung Hoon
authors.initials: BH
authors.lastname: Park
authors.forename: Jin Wook
authors.initials: JW
authors.lastname: Moon
authors.forename: Moo Suk
authors.initials: MS
authors.lastname: Park
authors.forename: Young Sam
authors.initials: YS
authors.lastname: Kim
authors.forename: Se Kyu
authors.initials: SK
authors.lastname: Kim
authors.forename: Joon
authors.initials: J
authors.lastname: Chang
authors.forename: Young Ae
authors.initials: YA
authors.lastname: Kang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001500:BCG Vaccine / Q000008:administration & dosage; D005260:Female; D006801:Humans; D016867:Immunocompromised Host; D007371:Interferon-gamma / Q000097:blood*; D055985:Latent Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014374:Tuberculin Test; D055815:Young Adult
chemical_list: D001500:BCG Vaccine; D007371:Interferon-gamma