SFTPD and interstitial lung disease: AE, acute exacerbation; ARF, acute respiratory failure; CT, computed tomography; HFNC, high-flow nasal cannula; IIP, idiopathic interstitial pneumonia; ILD, interstitial lung disease; IP, interstitial pneumonia; IPF, idiopathic pulmonary fibrosis; KL-6, Krebs von den Lungen-6; MV, mechanical ventilation; O2, oxygen therapy; OP, organizing pneumonia; PPV, positive predictive value; SP-D, surfactant protein-D; TP, true positive