Assessing Latent Tuberculosis Infections Prior to Biologic Therapy in Psoriasis: A New Diagnostic Approach with an Online Interpreter

Abstract

Abstract The use of biological agents, particularly anti-TNF-alpha treatments, in psoriasis patients is associated with an elevated risk of tuberculosis (TB). Hence, a comprehensive assessment of latent tuberculosis infection (LTBI) before biologic therapies is imperative. The objective of this study was to evaluate the utility of an online tuberculin skin test (TST)/ interferon-γ release assay (IGRA) interpreter (OI-TST/IGRA) in assessing the risk of LTBI prior to initiating biological therapies in psoriasis patients. One hundred-sixteen psoriasis patients who were previously evaluated for TB by a pulmonologist before being treated with a biologic agent were re-evaluated retrospectively with OI-TST/IGRA (tstin3d.com). Mean positive predictive value (PPV), mean annual risk of development of active tuberculosis (ARDATB), and mean cumulative risk of active tuberculosis (CRATB) values were calculated with OI-TST/IGRA and compared with previous results. Chi-square, Fisher-Freeman-Halton exact tests, Cohen's Kappa, and Mann-Whitney U-test were used in comparisons of groups. The PPV of the LTBI-positive group was significantly higher than the LTBI-negative group. The PPV, ARDATB and CRATB values of the TST size of > 15 mm group were significantly higher than the TST size of 5–9 mm and TST size of 10–15 mm groups. The PPV, ARDATB, and CRATB values of the QuantiFERON-TB Gold In-tube test (QFT-GIT)-positive group were significantly higher than the QFT-GIT-negative group. And the same values of the chest X-ray (CXR)-positive group were significantly higher than the CXR-negative group. The PPV, ARDATB, and CRATB values were positively correlated with QFT-GIT and CXR results. In addition, the PPV was positively correlated with previous LTBI decisions and TSTs. OI-TST/IGRA in which many factors are questioned and PPV, ARDATB, and CRATB values are evaluated together, may be a valuable tool for assessing the risk of active TB in psoriasis patients and preventing overdiagnosis and unnecessary prophylaxis.