MUC1 and idiopathic pulmonary fibrosis: Satoh et al., in 219 patients with ILD (IIP in 152 and CTD-ILD in 67), including 183 patients (83.5%) with a UIP pattern on HRCT, showed that an elevated KL-6 level (≥1000 U/mL) was associated with a poor prognosis (HR, 2.95; P < 0.001) after the adjustment for age and sex [43].