Pneumocystis Jirovecii Pneumonia in Japanese Patients with Rheumatoid Arthritis Treated with Tumor Necrosis Factor Inhibitors: A Pooled Analysis of 3 Agents.

Abstract

To the Editor: Pneumocystis jirovecii pneumonia (PCP) is an infectious fungal disease caused by P. jirovecii , which has attracted the attention of physicians treating patients with human immunodeficiency virus infection1, as well as those with connective tissue diseases, malignancies, and organ transplantation2. In patients with rheumatoid arthritis (RA), PCP used to be an uncommon infectious disease, but the number of case reports of PCP in patients with RA has increased since the introduction of low-dose methotrexate as an anchor drug for RA in the 1980s3. Moreover, with the introduction of anti-tumor necrosis factor (TNF) therapy, a further increase of incidence of PCP in patients with RA has been noticed, especially in Japan where strict postmarketing surveillance (PMS) programs have been conducted for patients with RA treated with TNF inhibitors4,5,6. The numbers of patients with RA with PCP in these PMS programs who were treated with infliximab (IFX), etanercept (ETN), or adalimumab (ADA) were 22 (0.4%) out of 50004, 25 (0.18%) out of 13,8945, and 25 (0.33%) out of 7469 patients6, respectively. Notably, these incidence rates of PCP in Japan are higher than the corresponding figure (0.01%) reported from the United States. Therefore, we previously analyzed the clinical characteristics and risk factors for PCP in patients with RA in Japan treated with these 3 TNF inhibitors7,8,9,10 … Address correspondence to Dr. M. Harigai, Department of Pharmacovigilance, Tokyo Medical and Dental University Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan. E-mail: mharigai.mpha{at}tmd.ac.jp