The univariate Cox proportional hazards model showed that older age, male sex, ever-smoker status, high levels of KL-6 (≥685 U/mL) and RF (≥88 IU/mL), lower FVC and DLco, shorter 6MWT distance, and a UIP pattern on HRCT were significantly related to mortality (Table 4). This evidence concerns the gene MUC1 and idiopathic pulmonary fibrosis.