Serial QuantiFERON-TB Gold In-Tube testing for psoriatic patients receiving antitumor necrosis factor-alpha therapy

Background/Objective Tumor necrosis factor-α (TNF-α) antagonists have become increasingly popular in the treatment of psoriasis. However, the increased risk of latent tuberculosis infection (LTBI) reactivation has also become an important issue in clinical practice. The aim of this study was to evaluate serial QuantiFERON-TB Gold In-Tube (QFT-GIT) testing for detecting LTBI among a cohort of psoriatic patients vaccinated with bacille Calmette-Guerin in a country with an intermediate burden of TB during long-term treatment with TNF-α antagonists. Methods We enrolled psoriatic patients treated with TNF-α antagonists who also accepted yearly serial QFT-GIT testing and regular chest X-ray examinations before and during the anti-TNF-α treatment from January 2010 to August 2014. Patients diagnosed with LTBI received chemoprophylaxis, and QFT-GIT testing was performed in these patients after completion of chemoprophylaxis. Results In this retrospective study, 101 patients had completed baseline and at least 1 year of follow-up. Among these patients, 60 had continued TNF-α antagonists therapy and received examinations in the 2 nd year, whereas 18 had continued the therapy until the 3 rd year. The conversion rate among these patients was 14.29% (13/91). In this study, 23 patients were diagnosed with LTBI according to the positive results obtained in the QFT-GIT test, with 19 of them having completed chemoprophylactic therapy. Follow-up QFT-GIT testing revealed reversion in 11 patients (57.89%) and decreased interferon-γ (IFN-γ) levels (68.42%) in 13 patients. Patients over 45 years of age tended to have a persistent positive result. Conclusion This study demonstrated that 14.29% of psoriatic patients undergoing long-term TNF-α antagonist therapy had a QFT-GIT conversion. Although a decreased IFN-γ level and QFT-GIT reversion were observed in most cases following prophylactic therapy, the value of QFT-GIT for evaluating the effect of LTBI prophylaxis remains controversial.