Concordance between tuberculin skin test and interferon-gamma release assay for latent tuberculosis screening in...

Latent tuberculosis screening is mandatory prior to initiating anti-tumor necrosis factor (anti-TNF) medications. Guidelines recommend interferon-gamma release assays (IGRA) as first line screening method for the general population. Studies provided conflicting evidence on IGRA and tuberculin skin test (TST) performance in inflammatory bowel disease (IBD) patients. We assessed test concordance and the effects of immunosuppression on their performance in IBD patients.

We searched MEDLINE, Embase and Cochrane databases (2011-2018) for studies testing TST and IGRA in IBD. Primary outcome was TST and IGRA concordance. Secondary outcomes were effects of immunosuppressive therapy on performance. Immunosuppression defined as either steroids, thiopurine, methotrexate or cyclosporine use. We used the pooled random effects model to adjust for heterogeneity analyzed using (I2-Q statistics). We compared the fixed model to exclude smaller study effects.

Sixteen studies (2,488 patients) were included. Pooled TST and IGRA concordance was 85% (95% confidence interval [CI], 81%-88%; P=0.01). Effects of immunosuppression were reported in 8 studies (814 patients). The odds ratio of testing positive by IGRA decreased to 0.57 if immunosuppressed (95% CI, 0.31-1.03; P=0.06). The odds ratio of testing positive by TST if immunosuppressed was 1.14 (95% CI, 0.61-2.12; P=0.69). The fixed model yielded similar results, however the negative effect of immunosuppression on IGRA reached statistical significance (P=0.01).

While concordance was 85% between TST and IGRA, the performance of IGRA seems to be negatively affected by immunosuppression. Given the importance of detecting latent tuberculosis prior to anti-TNF initiation, further randomized controlled trials comparing the performance of TST and IGRA in IBD patients are needed.