Interferon-gamma release assay as a diagnostic test for tuberculosis-associated uveitis

Eye (Lond). 2012 May;26(5):658-65. doi: 10.1038/eye.2012.1. Epub 2012 Feb 3.

Abstract

Background: To study the use of interferon-gamma release assay (IFN-γ) (IGRAs) as a diagnostic test for tuberculosis (TB)-associated uveitis (TAU).

Design: Prospective cohort study.

Participants: Consecutive new patients (n=162) with clinical ocular signs suggestive of TAU, seen >1 year period at a single tertiary center.

Methods: All subjects underwent investigations to rule out underlying disease, including T-SPOT.TB and tuberculin skin test (TST). Twenty-one subjects with underlying disease and three with interdeterminate T-SPOT.TB results were excluded. Those with T-SPOT.TB- or TST-positive results were referred to infectious diseases physician for evaluation. Anti-TB therapy (ATT) was prescribed if required. Patients' treatment response and recurrence were monitored for six months after completion of ATT, if given; or 1 year if no ATT was given.

Main outcome measure: Diagnosis of TAU.

Results: Mean age of study cohort (n=138) was 46.8 ± 15.3 years. Majority were Chinese (n=80, 58.0%) and female (n=75, 54.3%). TST was more sensitive than T-SPOT.TB (72.0% vs 36.0%); but T-SPOT.TB was more specific (75.0% vs 51.1%) for diagnosing TAU. Patients with either a T-SPOT.TB (1.44; 95% confidence intervals (CI), 0.86-2.42) or TST (1.47; 95% CI, 1.12-1.94)-positive result are more likely to have TAU. The accuracy of diagnosing TAU increases when both tests are used in combination (area under the receiver operator curve=0.665; 95% CI, 0.533-0.795). Patients with both tests positive are 2.16 (95% CI, 1.23-3.80) times more likely to have TAU. Negative T-SPOT.TB or TST results do not exclude TAU (negative likelihood ratios <1.0).

Conclusions: We recommend using a combination of clinical signs, IGRA, and TST to diagnose TAU.

Publication types

  • Comparative Study

MeSH terms

  • Area Under Curve
  • Cohort Studies
  • Ethnic Groups
  • False Positive Reactions
  • Female
  • Humans
  • Interferon-gamma
  • Interferon-gamma Release Tests*
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Prospective Studies
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Singapore / epidemiology
  • Tuberculin Test
  • Tuberculosis, Ocular / diagnosis*
  • Tuberculosis, Ocular / ethnology
  • Uveitis / diagnosis*

Substances

  • Interferon-gamma