Neutrophil-to-lymphocyte ratio in IPF patients: a novel prognostic biomarker?

Abstract

Introduction: Idiopathic pulmonary fibrosis (IPF) is a severe interstitial lung disease (ILD). Bronchoalveolar lavage (BAL) is useful for differential diagnosis of ILD and as a source of ILD biomarkers. BAL neutrophilia has been associated with rapid progression of disease while BAL lymphocytosis with less severe fibrotic involvement. Peripheral neutrophil-to-lymphocyte ratio (N/L) was proposed as a prognostic factor in several types of neoplastic and non-neoplastic lung disease but no data is available on ILD. Aim and Objectives: BAL N/L ratio has been evaluated in sarcoidosis (SA) and chronic Hypersensitivity Pneumonitis (cHP) compared with IPF patients. Methods: BAL samples from the 167 ILD patients were retrospectively enrolled and clustered into three diagnostic categories: IPF, cHP and SA. A decision-tree statistical algorithm was performed. Results: N/L was significantly higher in IPF than SA and cHP patients (fig.1a). Receiver operating curve (ROC) analysis discriminated between IPF and other ILD, according to DLco percentages and N/L ratio (fig.1b,c). A decision-tree statistical analysis to combine the prognostic biomarkers has been added (fig.1d). Conclusions: IPF showed the highest N/L ratio in BAL than SA and cHP. A relationship between BAL N/L and DLco was demonstrated in patients with IPF. This ratio can contribute to clinical management of IPF patients allowing to improve follow-up and outcome.