Serial Quantiferon-TB Gold test results in 279 patients with psoriasis receiving biologic therapy

The risk of active tuberculosis is still a concern in patients receiving biologics. To determine the risk of latent tuberculosis infection (LTBI) reactivation by Quantiferon-TB Gold (QFT) assay in psoriatic patients treated with biologics in 11 years' follow-up, along with chest radiography alterations. This retrospective study included 279 patients with plaque-type and/or pustular, or nail psoriasis who were treated with biologics, and had results for ≥2 LTBI tests. The QFT outcomes were defined according to the baseline and the follow-up QFT results; seroconversion as from negative to positive, seroreversion as from positive to negative, persistently seronegative as invariantly negative, persistently seropositive as invariantly positive, and other any result was accepted as indeterminate. Demographic features, the presence and the type of any chest X-ray abnormality was noted during the follow-up. Of 279 baseline QFT tests, the vast majority were negative (n = 193; 69%), with a less of positive (n = 86; 31%). Ten (5.2%) of 193 patients converted from negative to positive QFT status after starting biologic therapy (P < 0.001) during 11 years' follow-up. Although these 10 patients exhibited seroconversion of QFT from negative to positive, only one patient was diagnosed with active TB. There was no statistically significant difference among biologics as regards with QFT seroconversion risk (P = .09). This study showed that 5.2% of patients showed seroconversion. Annual QFT testing remains a necessary and mandatory tool to prevent further TB reactivation in psoriasis patients taking biologic therapy although only one patient was diagnosed with active TB in this cohort.