Latent tuberculosis infection in patients with chronic plaque psoriasis who are candidates for biological therapy

Summary Background Screening for latent tuberculosis infection (LTBI) is mandatory in patients with psoriasis prior to biological therapy. Objectives To investigate the prevalence of LTBI in patients with psoriasis who are candidates for biological therapy. Methods LTBI was investigated in patients with moderate-to-severe psoriasis (n = 243), Crohn disease (n = 64) or rheumatoid arthritis (RA) (n = 56) and in healthcare workers (n = 1683). LTBI diagnosis was based on positive QuantiFERON-B Gold In-Tube (QFT-GIT) in vitro assay without any clinical, radiological or microbiological evidence of active tuberculosis. Results LTBI was diagnosed in 8·2% of patients with psoriasis, 7% with Crohn disease and 9% with RA, and in 8·8% of healthcare workers (P = 0·9). Patients with psoriasis who also had LTBI (n = 20) received a 9-month prophylaxis with isoniazid (5 mg kg−1 daily). None of these patients developed active tuberculosis infection after receiving biological therapy (etanercept, adalimumab, infliximab or ustekinumab) for 37 ± 32 weeks (mean ± SD). All patients with psoriasis were retested for LTBI after 31 ± 1·7 months. Five of the 20 patients with LTBI presented QFT-GIT reversion and two patients out of 243 (0·8%) had QFT-GIT conversion and received antibiotic prophylaxis. Conclusions The prevalence of LTBI in patients with psoriasis is similar to that in patients with Crohn disease or RA and in healthcare workers. Prophylaxis with isoniazid is effective in preventing tuberculosis reactivation in patients with LTBI receiving biological therapy.