Negative effect of immunosuppressive therapy in the performance of the QuantiFERON gold in-tube test in patients with immune-mediated inflammatory diseases.

To compare the tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube test (QFG) for the detection of latent tuberculosis infection among patients with immune-mediated inflammatory diseases before antitumor necrosis factor-α therapy. A prospective study including 153 consecutive patients with rheumatoid arthritis (n = 53), psoriasis (n = 45), inflammatory bowel disease (n = 25), and spondyloarthropathy (n = 22) were included. QFG and TST were performed simultaneously. TST was positive in 43/153 (28.1 %) patients. QFG (cutoff ≥ 0.35 IU/ml) was positive in 15/153 (9.8 %) patients, and indeterminate in one (0.7 %). QFG (cutoff ≥ 0.10 IU/ml) was positive in 25/153 (16.3 %). 59.5 % of the patients were on immunosuppressive therapy at the time of testing. There was a significant difference in the rate of positive QFG between patients with and without immunosuppressive therapy after adjustment for age and gender (cutoff ≥ 0.35 IU/ml, 4.6 vs. 17.4 %; adjusted odds ratio [AOR], 0.2; 95 % confidence interval [CI], 0.06-0.8; p = 0.03 and cutoff ≥ 0.10 IU/ml, 11.2 vs. 24.2 %; AOR, 0.3; 95 % CI, 0.1-0.93; p = 0.04). Agreement between TST and QFG was 'fair' (κ = 0.354 and κ = 0.365, for cutoffs ≥ 0.35 and ≥0.10 IU/ml, respectively). Among patients without immunosuppressive therapy, the concordance between TST and QFG was 'moderate-substantial' (κ = 0.593 and κ = 0.690, for cutoffs ≥ 0.35 IU/ml and ≥0.10 IU/ml, respectively). By contrast, among patients on immunosuppressive therapy the concordance was 'poor' (κ = 0.085; κ = 0.041, respectively). Immunosuppressive therapy affects negatively QFG performance. In patients with immune-mediated inflammatory diseases, QFG may have a limited role for screening of latent tuberculosis infection.