Fig. 1

Cumulative incidence of acute exacerbation (AE), survival curves, causes of death in patients with idiopathic interstitial pneumonia (IIP). The incidence rates of AE-IIP (A) at 1, 2, 3, 4, and 5 years after the initial diagnosis of IIP were 6.5%, 10.1%, 13.6%, 18.8%, and 18.8%, respectively. The most common cause of death was AE-IIP (36.4%) (B). Kaplan-Meier curves of survival in patients with and without AE-IIP show that the mortality rate was significantly lower in patients who experienced AE-IIP (p < 0.001) (C). There is no significant difference in the proportion of IIP subtypes between patients with and without AE-IIP (D). AE, acute exacerbation; IIP, idiopathic interstitial pneumonia; IPF, idiopathic pulmonary fibrosis; IPAF, interstitial pneumonia with autoimmune symptoms; NSIP, nonspecific interstitial pneumonia; COP, cryptogenic organizing pneumonia; SR-ILD, smoking-related interstitial lung disease; PPFE, pleuroparenchymal fibroelastosis; NSIP with OP, nonspecific interstitial pneumonia with organizing pneumonia; AIP, acute interstitial pneumonia.