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Effect of Immunosuppressive Therapy on Interferon Gamma Release Assay for Latent Tuberculosis Screen

SH Wong, Q Gao, KKF Tsoi, WKK Wu, LS Tam, N Lee, FKL Chan, JCY Wu, JJY Sung, and SC Ng, Thorax. 01, 2016. 71: p. 64-72.

Interferon γ release assay (IGRA) is commonly used to diagnose latent TB infection (LTBI). We aimed to determine the effect of immunosuppressive therapy on the performance of IGRA in patients with autoimmune diseases.

We searched PubMed, MEDLINE, EMBASE and the Cochrane Library up to December 2014 and included studies that reported the IGRA results in patients with autoimmune disease with or without immunosuppressive therapy. Seventeen studies with 3197 participants were included in the meta-analysis. Among the subjects, 71.5% were taking immunosuppressive therapy and 56.7% had received Bacillus Calmette-Guérin vaccination. Compared with patients not on immunosuppressants, patients receiving immunosuppressive therapy were less likely to have a positive IGRA result, especially patients receiving anti-tumour necrosis factor (anti-TNF) treatment. The use of immunosuppressive therapywas also associated with a lower rate of positive tuberculin skin test result. Our meta-analysis showed that IGRA results are negatively affected by immunosuppressive therapy. Patients should preferably be screened for LTBI before initiation of immunosuppressive therapy, especially before anti-TNF therapy.

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