The KL-6 level in progressive ILD was 325.98 (U/ml) higher than in non-progressive ILD (Figure 3), and HR (95%CI) for increased KL-6 level predicting the progression of ILD was 1.98 (1.07–3.67) (Figure 5), and the elevated KL-6 could effectively recognize the progressive ILD, particularly in idiopathic inflammatory myopathy associated interstitial lung disease (IIM-ILD) and indium exposure ILD (Supplementary Figure 1). Here, MUC1 is linked to acquired idiopathic inflammatory myopathy.