Serum pro SP-B levels exhibited the most significant associations with mortality in patients with ILD (HR 2.35; 95% CI 1.27–4.36; P = 0.0051 by log-rank test), although no significant association was found in patients with IPF (HR 1.28; 95% CI 0.60–2.73; P = 0.53 by log-rank test) and in patients with non-IPF-ILD (HR 2.26; 95% CI 0.82–6.25; P = 0.11 by log-rank test) (Supplementary Fig. S4A–C). Here, SFTPB is linked to idiopathic pulmonary fibrosis.