In patients with IPF with high baseline KL-6 levels (≥ 500 U/mL, n = 144), relative changes in KL-6 levels (over 1 month) were useful for predicting DP (area under the curve = 0.707, p = 0.029) in the ROC curve analysis (Fig. 3); the best cut-off level was a 5% increase (sensitivity = 64.7%; specificity = 75.6%). Here, MUC1 is linked to idiopathic pulmonary fibrosis.