MUC1 and idiopathic pulmonary fibrosis: Ko et al., among 199 patients with ILD (IPF = 43; 19.6% received antifibrotic agent), showed that a high baseline KL-6 level (≥ 800 U/mL) was a poor prognostic factor for DP (≥ 10% relative decline in FVC from baseline or AE over 1 year after diagnosis) (hazard ratio [HR], 2.689; 95% CI 1.445–5.004; p = 0.002) in the multivariable Cox analysis adjusted for by age, FVC, and lowest oxygen saturation during 6MWT [19].