Although rare, tuberculosis has been reported with biologic treatment against psoriasis in Japan, a tuberculosis medium-burden country. Mycobacterial infection often develops after a long incubation period and might not have been adequately identified in clinical trials or post-marketing surveillance. To determine the real-world incidence of tuberculosis in psoriatic patients treated with biologics, we conducted a retrospective, multicenter, observational study in 18 facilities in Western Japan. Psoriatic patients who visited a participating facility between 2010 and March 2017 and received biologic reagents were enrolled. Information on sex, age at first biologic treatment, results of interferon-γ release assay (IGRA) for Mycobacterium tuberculosis, treatment history with isoniazid, and onset of active and/or latent tuberculosis was collected. A total of 1117 patients (830 men and 287 women) were enrolled. The mean duration of biologic treatment was 3.54 years. Sixty-five patients (5.8%) showed positive IGRA results at screening. Active tuberculosis developed in two patients after the administration of tumor necrosis factor inhibitors (both involved miliary tuberculosis). Latent tuberculosis was observed in two patients treated with anti-interleukin-12/23p40 antibody. The incidence rate of tuberculosis, including latent tuberculosis, in this survey was 0.36%. Although the incidence rate of tuberculosis was low considering the observation period of biologic treatment, active tuberculosis was found in both the screening-negative group and a screening-positive subject after isoniazid prophylaxis (both miliary tuberculosis), concluding that negative screening or isoniazid treatment does not always assure that an individual has no tuberculosis. Hence, dermatologists still need to pay careful attention to tuberculosis at every patient visit.
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