MUC1 and idiopathic pulmonary fibrosis: A comparison of KL-6, SP-A, and SP-D for the diagnostic values in patients with ILD including IPF previously demonstrated that KL-6 was superior to other markers [6], and the findings of present study for IPF regarding the order of the AUC values obtained from ROC curves is the same as that study [6], in which KL-6 preceded SP-A and SP-D.