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

Ang M, Wong W, Ngan CC, Chee SP - Eye (Lond) (2012)

Bottom Line: Those with T-SPOT.TB- or TST-positive results were referred to infectious diseases physician for evaluation.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.Negative T-SPOT.TB or TST results do not exclude TAU (negative likelihood ratios <1.0).

View Article: PubMed Central - PubMed

Affiliation: Singapore National Eye Centre, National University of Singapore, Singapore, Singapore.

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.

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Related in: MedlinePlus

AUC combining tuberculin skin test (T) and T-SPOT.TB (S).
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fig4: AUC combining tuberculin skin test (T) and T-SPOT.TB (S).

Mentions: When both T-SPOT.TB and TST are used in combination, the overall accuracy for predicting TAU increases to 69.0% (95% CI, 57.5–78.6%) with a higher AUC of 0.665 (95% CI, 0.533–0.795) — Figure 4. If both tests are positive (S+T+), the positive likelihood ratio is 2.16 (95% CI, 1.23–3.80). In patients with both tests negative, 82.2% (37/45) patients resolved with no recurrence despite treatment without ATT. However, the negative likelihood ratio was <1.0 for patients with both tests negative (0.54; 95% CI, 0.30–0.99). The concordance of both tests was low (κ-value=0.085 (P=0.239)) in our study cohort. Discordant results were found in 67/138 (48.6%) cases. In these patients, the positive likelihood ratios were comparable in patients with S+T− (1.44; 95% CI, 0.86–2.42) and S−T+ (1.47; 95% CI, 1.12–1.94); whereas the negative likelihood ratios were <1.0 for patients with S+T− (0.85; 95% CI, 0.67–1.09) and S−T+ (0.54; 95% CI, 0.34–0.89). No significant risk factors were identified for discordant results such as age (P=0.38), gender (P=0.73), race (P=0.33), or type of uveitis (P=0.54). We used the observed prevalence of TAU to compare the prior probability of disease with the positive and negative predictive values (PPV and NPV, respectively). Although T-SPOT.TB and TST each had a greater PPV (45.0% and 45.6%, respectively vs the prior probability of 36.2% — an improvement of 9%), combining the test results improved the PPV over the prior probability by 17%.


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

Ang M, Wong W, Ngan CC, Chee SP - Eye (Lond) (2012)

AUC combining tuberculin skin test (T) and T-SPOT.TB (S).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3351054&req=5

fig4: AUC combining tuberculin skin test (T) and T-SPOT.TB (S).
Mentions: When both T-SPOT.TB and TST are used in combination, the overall accuracy for predicting TAU increases to 69.0% (95% CI, 57.5–78.6%) with a higher AUC of 0.665 (95% CI, 0.533–0.795) — Figure 4. If both tests are positive (S+T+), the positive likelihood ratio is 2.16 (95% CI, 1.23–3.80). In patients with both tests negative, 82.2% (37/45) patients resolved with no recurrence despite treatment without ATT. However, the negative likelihood ratio was <1.0 for patients with both tests negative (0.54; 95% CI, 0.30–0.99). The concordance of both tests was low (κ-value=0.085 (P=0.239)) in our study cohort. Discordant results were found in 67/138 (48.6%) cases. In these patients, the positive likelihood ratios were comparable in patients with S+T− (1.44; 95% CI, 0.86–2.42) and S−T+ (1.47; 95% CI, 1.12–1.94); whereas the negative likelihood ratios were <1.0 for patients with S+T− (0.85; 95% CI, 0.67–1.09) and S−T+ (0.54; 95% CI, 0.34–0.89). No significant risk factors were identified for discordant results such as age (P=0.38), gender (P=0.73), race (P=0.33), or type of uveitis (P=0.54). We used the observed prevalence of TAU to compare the prior probability of disease with the positive and negative predictive values (PPV and NPV, respectively). Although T-SPOT.TB and TST each had a greater PPV (45.0% and 45.6%, respectively vs the prior probability of 36.2% — an improvement of 9%), combining the test results improved the PPV over the prior probability by 17%.

Bottom Line: Those with T-SPOT.TB- or TST-positive results were referred to infectious diseases physician for evaluation.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.Negative T-SPOT.TB or TST results do not exclude TAU (negative likelihood ratios <1.0).

View Article: PubMed Central - PubMed

Affiliation: Singapore National Eye Centre, National University of Singapore, Singapore, Singapore.

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.

Show MeSH
Related in: MedlinePlus