Background:: Reactivation of latent Mycobacterium tuberculosis (TB) is a rare, yet devastating infectious complication associated with anti‐tumor necrosis factor alpha (TNF‐α) therapy. We evaluated the performance of the QuantiFERON TB Gold test (QFT‐G) for TB screening in a cohort of inflammatory bowel disease (IBD) patients in the United States.
Methods:: We performed a retrospective, observational study of patients initiated and/or maintained on an anti‐TNF‐α agent in a single IBD referral center and recorded the frequency and the test results of QFT‐G testing and the rate of TB reactivation.
Results:: 512 QFT‐G tests were done in 340 patients. Five patients (1.5%) had a positive, nine (2.7%) indeterminate, and 326 patients (95.8%) had a negative QFT‐G. After a mean follow‐up of 17 months there was one case of TB reactivation (0.3%). The use of immunosuppressive therapy or anti‐TNF therapy at the time of testing did not affect the results of the QFT‐G testing. Test–retest had substantial concordance (κ = 0.72). 25% of patients (n = 85) had TST testing. Concordance between the TST and QFT‐G was found to be moderate (κ = 0.4152, P = 0.0041).
Conclusions:: Most patients with negative QFT‐G tolerated anti‐TNF therapy with no evidence of TB reactivation. Concomitant use of immunosuppressive therapy or anti‐TNF did not seem to affect QFT‐G results. One patient had an indeterminate QFT‐G while on infliximab and later developed miliary TB. Concordance with TST is moderate. (Inflamm Bowel Dis 2011;)