MUC1 and silicosis: Univariate and multivariate analyses were carried out to test whether serum KL-6, in addition to other covariates [age, gender, smoking history, body mass index (BMI), FVC % predicted, serum CRP and LDH, and Neutrophil-to-lymphocyte ratio (NLR)], is a predictor of silicosis onset in silica-exposed workers, as shown in Table 3a.