Screening and monitoring of latent tubercular infection in patients taking tumor necrosis factor-α blockers for psoriatic arthritis.

Patients with arthritis who need treatment with biologics are carefully screened for possible previous exposure to tuberculosis to detect any latent tubercular infection (LTBI). The traditional method of screening for LTBI is not specific, because positivity could also depend on infection by atypical mycobacteria and bacillus Calmette-Guerin vaccination. In addition, the screening does not show high sensitivity, frequently presenting a false negativity because of immunosuppression caused by drugs used for arthritis. Recently, interferon-γ release assays (IGRA) have been used to screen LTBI with more sensitivity and specificity before treatment with anti-tumor necrosis factor-α drugs. Moreover, in our experience, IGRA are potentially useful in monitoring LTBI during biologic therapy.