Quantiferon-TB Gold in tube assay for the screening of tuberculosis before and during treatment with tumor necrosis factor alpha antagonists

Abstract

IntroductionThe usefulness of interferon-gamma (IFN-γ) release assays for tuberculosis screening before tumor necrosis factor-alpha (TNF-α) antagonists and for monitoring during treatment is a contraversial issue. The aims of this study were to determine whether TNF-α antagonists affect the results of the Quantiferon-TB Gold in-tube assay (QTF); to assess how QTF performs in comparison with the tuberculin skin test (TST) in rheumatoid arthritis (RA) patients who are about to start treatment with TNF-α antagonists, RA patients who are not candidates for treatment with TNF-α antagonists, rheumatology patients with confirmed current or past tuberculosis infection, and healthy controls, and to determine the specificity of the QTF test to differentiate leprosy patients, another group of patients infected with mycobacteria.MethodsThe 38 RA patients who were prescribed TNF-α antagonists, 40 RA patients who were not considered for TNF-α antagonist use, 30 rheumatology patients with a history or new diagnosis of tuberculosis, 23 leprosy patients, and 41 healthy controls were studied. QTF and TST were done on the same day, and both were repeated after a mean of 3.6 ± 0.2 months in patients who used TNF-α antagonists.ResultsTreatment with TNF-α antagonists did not cause a significant change in the QTF or TST positivity rate (34% versus 42%; P = 0.64; and 24% versus 37%; P = 0.22). Patients with leprosy had a trend for a higher mean IFN-γ level (7.3 ± 8.0) and QTF positivity (61%) than did the other groups; however, the difference was not significant (P = 0.09 and P = 0.43).ConclusionsTreatment with TNF-α antagonists does not seem to affect the QTF test to an appreciable degree. The higher IFN-γ levels in leprosy patients deserves further attention.

Unaffected reaction level in tuberculin skin test by long‐term therapy with tumor necrosis factor inhibitors for rheumatoid arthritis

“…Our results are in agreement with those reported from Spain, Turkey and Austria, although there are some methodological differences. BCG vaccination is routinely performed in Turkey, as in Japan.…”

“…Several authors have recommended repeating the TST because an initial negative test becomes positive in some patients during therapy with TNF inhibitors, signifying either reactivation of TB or new infection . However, there have been few reports regarding the influence of TNF inhibitors on the results of the TST …”

Frequent conversion of tuberculosis screening tests during anti-tumour necrosis factor therapy in patients with rheumatic diseases

“…In general, the rate of conversion was higher in high TB prevalence countries. For example, for the TST the conversion rate was 0–12% in low prevalence countries (Italy,17 20 Austria19) increasing to 25–37% in high prevalence areas (Turkey,18 Taiwan,15 Korea16). None of these studies examined all three assays in parallel and no risk factors for assay conversion were identified with the exception of one study where administration of anti-TNFs for more than 3 years was associated with TST conversion 16…”

Effect of immunosuppressive therapy on interferon γ release assay for latent tuberculosis screening in patients with autoimmune diseases: a systematic review and meta-analysis

“…This study provides support for this recommendation, as potent immunosuppressive therapy can undermine the IGRA result significantly (Peto OR=0.50). This is likely due to the suppression of interferon γ and stimulation of immune cell apoptosis 33 34. There is a concern that IGRA may not be sensitive in patients already on anti-TNF.…”