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


METHODS
Prospective cohort study.


METHODS
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.


METHODS
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.
Singapore National Eye Centre, National University of Singapore, Singapore, Singapore.
M
M
Ang
W
W
Wong
C C L
CC
Ngan
S-P
SP
Chee
D019540:Area Under Curve; D015331:Cohort Studies; D005006:Ethnicity; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007371:Interferon-gamma; D059425:Interferon-gamma Release Tests; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012846:Singapore / Q000453:epidemiology; D014374:Tuberculin Test; D014392:Tuberculosis, Ocular / Q000175:diagnosis* / Q000208:ethnology; D014605:Uveitis / Q000175:diagnosis*
D007371:Interferon-gamma