Fig. 3

Scatter diagram for the relationship between serum S1P level and pulmonary function indexes by linear regression analyses (TLC% pred, FVC% pred and FEV1% pred) in IPF patients (A, B, C and D) and CTD-ILD patients (D, E, F and G). IPF, idiopathic pulmonary fibrosis; CTD-ILD, connective tissue disease-associated interstitial lung disease; TLC% pred, predicted total lung capacity; FVC% pred, predicted forced vital capacity; FEV1%pred, Forced expiratory volume in the first second