Dermatology & Plastic Surgery Institute Outcomes

Limited data exist about the incidence of conversion to positive latent tuberculosis infection (LTBI) in hidradenitis (HS) patients treated with biologics1,2. Given this, and because other biologics are being studied as HS treatments, Cleveland Clinic physicians reviewed LTBI screening results in HS patients treated with biologics.

HS patients treated for ≥3 months with a biologic (for HS or an associated condition) and ≥2 documented LTBI test results (QuantiFERON-TB Gold (QFT)) were identified from 2007– 2019. For patients with either positive or indeterminate QFT results, a retrospective review of medical records was performed to extract clinical data, including demographics, biologic treatment, number of QFT tests, QFT results, TB risk factors, and treatment. Analyses included calculating means, overall counts, and percentages.

One hundred seventy HS patients met inclusion/exclusion criteria. Seventy-two patients were treated with >1 biologic, with an average of 1.7 unique biologics per patient. The most frequently prescribed biologics were TNFIs. Adalimumab was the most common biologic, followed by infliximab, etanercept, and ustekinumab. The cohort had 521 QFT tests, with an average of 3.06 tests per patient. Of 170 patients, 143 (84.1%) had only negative QFT results, 18 (10.6%) had ≥1 indeterminate result, and 9 (5.3%) had ≥1 positive result. Four patients (2.4%) converted from initial negative QFT testing to positive. Two of 4 converters had documented TB risk factors. Additionally, 2 of 4 converters were being treated with TNFIs (infliximab and adalimumab) at time of conversion, while the other 2 patients were taking other medications. Only 4 of 9 patients with positive QFT results were treated for LTBI, 3 of whom were converters. No patient developed active TB.

The results suggest routine serial LTBI testing of HS patients in low-risk areas taking biologics may be unnecessary. False positive and indeterminate test results in this population may lead to further testing, referrals, unnecessary treatment, adverse events, and excessive healthcare costs. Additional research is needed to improve screening guidelines regarding LTBI testing for HS patients receiving biologic therapy.