Fig. 1

Study flowchart. BAL bronchoalveolar lavage, COP cryptogenic organizing pneumonia, CTD-ILD connective tissue disease-associated interstitial lung disease, DIP desquamative interstitial pneumonia, HP hypersensitivity pneumonia, IIP idiopathic interstitial pneumonia, iNSIP idiopathic non-specific interstitial pneumonia, IPF idiopathic pulmonary fibrosis, iPPFE idiopathic pleuroparenchymal fibroelastosis, MDD multidisciplinary discussion, RB-ILD respiratory bronchiolitis-associated interstitial lung disease. Of the 465 cases analyzed in the previous study [17], 200 cases diagnosed with IPF, 5 cases diagnosed with COP, and 9 cases diagnosed with DIP/RB-ILD by MDD were excluded. Twenty-one cases diagnosed with ILD other than IIPs [HP (n = 12), CTD-ILD (n = 5), lymphoproliferative disease (n = 3), and invasive mucinous adenocarcinoma (n = 1)] were also excluded. Of the 230 patients with fibrotic IIPs other than IPF, 44 cases for whom BAL was not performed were excluded. Finally, 186 patients were included for analysis