Fig. 1.

Flowchart of cohort selection for main analyses. Subgroup analyses are not included in this flowchart. IPF cohort existed of n = 61 patients. *Subgroups reduced to size n = 55 by random selection. **If group size ≥ 30, cohorts were split in a training and test set. COPD = chronic obstructive pulmonary disease; LC = lung cancer; ILD = interstitial lung disease; IPF = idiopathic pulmonary fibrosis; PLS-DA = partial least squares discriminant analysis