PT  - JOURNAL ARTICLE
AU  - Noriyuki Enomoto
AU  - Sakae Homma
AU  - Naohiko Inase
AU  - Yasuhiro Kondoh
AU  - Takeshi Saraya
AU  - Hajime Takizawa
AU  - Yoshikazu Inoue
AU  - Hiroshi Ishii
AU  - Yoshio Taguchi
AU  - Shinyu Izumi
AU  - Yasuhiko Yamano
AU  - Yoshinori Tanino
AU  - Yasuhiko Nishioka
AU  - Mikio Toyoshima
AU  - Koshi Yokomura
AU  - Shiro Imokawa
AU  - Naoki Koshimizu
AU  - Takehisa Sano
AU  - Taisuke Akamatsu
AU  - Hiroshi Mukae
AU  - Motoyasu Kato
AU  - Naoki Hamada
AU  - Hirofumi Chiba
AU  - Shinobu Akagawa
AU  - Shigeo Muro
AU  - Hironori Uruga
AU  - Hiroyuki Matsuda
AU  - Yusuke Kaida
AU  - Miho Kanai
AU  - Kazutaka Mori
AU  - Masafumi Masuda
AU  - Hironao Hozumi
AU  - Tomoyuki Fujisawa
AU  - Yutaro Nakamura
AU  - Noriyoshi Ogawa
AU  - Takafumi Suda
TI  - Prospective nationwide multicentre cohort study of the clinical significance of autoimmune features in idiopathic interstitial pneumonias
AID  - 10.1136/thoraxjnl-2020-216263
DP  - 2021 Jul 15
TA  - Thorax
PG  - thoraxjnl-2020-216263
4099  - http://thorax.bmj.com/content/early/2021/07/15/thoraxjnl-2020-216263.short
4100  - http://thorax.bmj.com/content/early/2021/07/15/thoraxjnl-2020-216263.full
AB  - Background Some patients with idiopathic interstitial pneumonia (IIP) show autoimmune features. Interstitial pneumonia with autoimmune features (IPAF) was recently proposed as a research concept in these patients. However, retrospective studies reported conflicting results of its prognosis. Therefore, this study was conducted to prospectively evaluate the clinical significance of autoimmune features in patients with IIP.Methods This nationwide multicentre study prospectively enrolled consecutive patients with IIP. At the diagnosis, we systematically evaluated 63 features suggestive of connective tissue diseases using a checklist including symptoms/signs and autoantibodies, which contained most items of the IPAF criteria and followed up with the patients. Clinical phenotypes were included in a cluster analysis.Results In 376 patients with IIP enrolled, 70 patients (18.6%) met the IPAF criteria. The proportion of patients with IPAF was significantly lower in idiopathic pulmonary fibrosis (IPF) than in non-IPF (6.0% vs 24.3%, respectively). During a median observation period of 35 months, patients with IPAF more frequently developed systemic autoimmune diseases and had less frequent acute exacerbation of IIPs than patients with non-IPAF. IPAF diagnosis was significantly associated with better survival and was an independent positive prognostic factor in total and patients with non-IPF. Cluster analysis by similarity of clinical phenotypes identified a cluster in which there was a higher number of women, and patients had more autoimmune features and a better prognosis than other clusters.Interpretation These observations suggest that some patients with IIP show autoimmune features with distinct characteristics and favourable prognosis. However, we were not able to determine the appropriate therapies for these patients.All data relevant to the study are included in the article or uploaded as supplementary information.