Abstract
Introduction: The treatment of chronic inflammatory diseases has been transformed with targeted biologic therapies. Patients receiving this treatment are at increased risk of reactivating latent tuberculosis infection (LTBI). Tuberculin skin test (TST) has been the gold standard for detecting latent LTBI, but may be difficult to interpret in patients receiving immunosuppressive therapies. In vitro interferon-gamma-release assays (IGRA) are an alternative.
Aim: Evaluate and compare the effectiveness of IGRA (QFR-TB Gold In Tube assay [QFR] and T-SPOT.TB [TSTB]) against TST in a cohort of patients due to commence biological therapies.
Methods: A prospective cross sectional study was conducted at an inner London tertiary referral centre. Patients were screened for LTBI and a TST was performed. Venous blood samples were obtained for QFR and TSTB.
Results: 102 patients were included, aged between 18 and 83 years. A total of 42 patients were receiving at least one immunosuppressive therapy. A TST result was available in 84 patients. The overall agreement between the QFR vs TSTB excluding the indeterminate results was 69 out 78 (k=0.572), between QFR vs TST was 62 out of 79 (k=0.241) and between TSTB vs TST was 58 out of 72 (k=0.304). 13 patients received chemoprophylaxis for presumed LTBI.
Conclusion: Our study showed variation in results obtained from TST and IGRA's when used in our population, some of whom where immune compromised. For patients where interpretation of the results may prove challenging, LTBI screening tests may be best used in combination
- © 2011 ERS
