The red blood cell distribution width is independently associated with idiopathic pulmonary fibrosis

BACKGROUND: It is well known that inflammation-driven pathways play a significant pathogenic role in idiopathic pulmonary fibrosis (IPF). We assessed whether the red blood cell distribution width (RDW) and the mean platelet volume (MPV), often related to inflammatory diseases, are associated with IPF. METHODS: RDW and MPV were measured in 77 IPF patients and 62 controls matched for age, sex and smoking status. RESULTS: The RDW, but not the MPV, were significantly higher in IPF patients than controls (median: 14.0%; IQR: 13.2-14.9% vs. 13.1%; IQR: 12.3-13.9%, P=0.00003). In logistic regression, the significant association between RDW and IPF (OR=1.924; 95%CI: 1.347-2.749, P=0.0003) was independent of the percent forced expiratory volume at 1 sec (þV1) and forced vital capacity (%FVC). The combined RDW-%FVC-þV1 area under the curve (AUC=0.855, 95% CI: 0.785-0.909, P<0.0001) was significantly higher than that of individual components and their two-component combinations, with a 78% sensibility and 84% specificity. CONCLUSIONS: The RDW might represent a clinically suitable marker particularly in combination with lung functional parameters %FVC and þV1 for the diagnosis of IPF.