Subgroup analysis revealed that FVC decline was largely associated with higher COL1A1 mRNA in non-IPF patients (n=36) (R=-0.56, p=0.004, Spearman correlation), but not in IPF (n=33) (R=-0.084, p=NS, Spearman correlation) (Figures 6, A–C).When ILD patients were dichotomized in two categories, stable and progressive ILD, as defined by FVC decline of 10% or more, progressive ILD patients had higher mean COL1A1 mRNA levels compared to stable ILDs (Figures 6D–F). Here, COL1A1 is linked to idiopathic pulmonary fibrosis.