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Does an interferon-gamma release assay change practice in possible latent tuberculosis?
J F Tiernan1, S Gilhooley, M E Jones
1Department of Respiratory Medicine and TB Clinic, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh, Midlothian EH16 4SA, UK. james.tiernan@nhs.net
QJM : Monthly Journal of the Association of Physicians
|November 20, 2012
Summary
Interferon-gamma release assays (IGRAs) significantly altered clinical practice for suspected latent tuberculosis infection (LTBI) management. This testing strategy helped avoid unnecessary TB chemoprophylaxis in many patients.
Area of Science:
- Infectious Diseases
- Clinical Diagnostics
- Public Health
Background:
- Latent tuberculosis infection (LTBI) diagnosis is a frequent reason for referral to TB clinics.
- Interferon-gamma release assays (IGRAs) offer higher specificity than tuberculin skin tests (TSTs) for LTBI detection.
- Evaluating the impact of IGRA on clinical decision-making in TB referrals is crucial.
Purpose of the Study:
- To ascertain whether the implementation of IGRA influences the management protocols for patients referred to TB clinics with suspected LTBI.
- To assess the diagnostic utility of IGRA in comparison to TST in a real-world clinical setting.
Main Methods:
- A prospective study was conducted over 29 months, including adult patients with TST, CXR, and IGRA results.
- Initial management decisions for TB chemoprophylaxis were based on clinical history and TST results.
- Cases were re-evaluated with IGRA data to determine any changes in management, with subsequent independent physician review.
Main Results:
- Of 204 patients, 68 were immunocompromised. 120 had positive TSTs, with 36 (30%) testing positive and 84 (70%) negative by IGRA (QFT).
- Clinical practice changed in 65% of positive TST cases, with IGRA results leading to the avoidance of TB chemoprophylaxis.
- Among immunocompromised patients, 25% experienced a change in management due to IGRA results. No active TB cases developed.
Conclusions:
- The use of IGRA demonstrably leads to significant shifts in clinical practice for LTBI management.
- These findings align with and support existing recommendations, such as those from NICE 2011.
- IGRA implementation can optimize TB chemoprophylaxis decisions, particularly in complex cases.
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