Interferon-gamma release assay performance in pulmonary and extrapulmonary tuberculosis

Yun Feng, Ni Diao, Lingyun Shao, Jing Wu, Shu Zhang, Jialin Jin, Feifei Wang, Xinhua Weng, Ying Zhang, Wenhong Zhang

Research output: Contribution to journalArticlepeer-review

Abstract

Background: The diagnosis of tuberculosis remains difficult. This study aimed to assess performance of interferon-gamma release assay (IGRA) in diagnosis of active tuberculosis (ATB) with pulmonary and extrapulmonary involvements, and to determine the diagnostic role of IGRA (T-SPOT.TB) and tuberculin skin test (TST) in BCG-vaccinated population. Methods and Findings: Two hundred twenty-six ATB suspects were recruited and examined with T-SPOT.TB. Among them, fifty-two and seventy-six subjects were simultaneously tested by TST with 5TU or 1TU of purified protein derivative (PPD). The sensitivity of T-SPOT.TB was 94.7% (71/75), comparable in pulmonary and extrapulmonary disease groups (95.6% vs. 93.3%, P&0.05), while the specificity was 84.10% (90/107) but differed in two groups (69.2% vs. 88.9%, P = 0.02). Compared to T-SPOT.TB, TST with 5TU-PPD showed less sensitivity (92.3% vs. 56.4%) and specificity (84.6% vs. 61.5%) (both P<0.01); the sensitivity of TST with 1TU-PPD was 27.8%, and despite its specificity identical to T-SPOT.TB (both 82.8%) positive predictive value (PPV) was only 33.3%. By combining T-SPOT.TB with TST (1TU), the specificity rose to 95%, but the PPV stayed unchanged. Conclusions: IGRA could function as a powerful immunodiagnostic test to explore pulmonary and extrapulmonary TB, while TST failed to play a reliable or auxiliary role in identifying TB disease and infection in the BCG-vaccinated population.

Original languageEnglish (US)
Article numbere32652
JournalPloS one
Volume7
Issue number3
DOIs
StatePublished - Mar 13 2012

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

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