Reactivation of LTBI in patients with IBD on anti-TNF-α agents can lead to serious life-threatening illness. No gold standard exists for the detection of LTBI. We examined whether a dual testing strategy with TST and IGRA would improve the detection of LTBI.
Consecutive IBD patients being considered for anti-TNF-α treatment underwent testing with a TST, IGRA and CXR. All patients completed a self-administered questionnaire. The association of both tests with demographic factors, LTBI risk factors, BCG vaccination, IS therapy and agreement between the TST and IGRA were evaluated.
One-hundred and fifty-five IBD patients were included, 6% were TST positive and 5% were IGRA positive. Concordance between TST and IGRA was fair (κ = 0.21, 95% CI - 0.081-0.498). Neither test was affected by age, gender or BCG vaccination. The presence of risk factors for LTBI was found to be positively associated with TST (OR 19.8, 95% CI 3.9-102.1), but not IGRA. IGRA was negatively associated with IS therapy (OR 0.06, 95% CI 0.007-0.5), but not TST. Four patients who were IGRA positive but TST negative were treated for LTBI by a respirologist.
An IGRA result was negatively associated with IS therapy, while the presence of risk factors for LTBI was found to be positively associated with TST results. There was fair agreement between positive TST and IGRA results. The addition of IGRA to the standard practice of TST and CXR increased the number of cases that were initiated on LTBI therapy.