Fig. 4

Cumulative incidence of acute exacerbation. a Clusters II (green line) and III (blue line) had significantly higher cumulative incidence rates of acute exacerbation than Cluster IV (orange line, both p = 0.03). b Patients with idiopathic pulmonary fibrosis (IPF, continuous line) had a significantly higher cumulative incidence rate of acute exacerbations than those with cryptogenic organizing pneumonia (COP, small dashed line, p = 0.01) and unclassifiable IIPs (long dashed short dashed line, p < 0.01), whereas there was no significant difference among the other idiopathic interstitial pneumonia groups. DIP/RB-ILD, desquamative interstitial pneumonia/respiratory bronchitis-associated interstitial lung disease (middle dashed line); NSIP, non-specific interstitial pneumonia (dotted line); PPFE, pleuroparenchymal fibroelastosis (long dashed line)