Interstitial lung disease: performance of neutrophil-lymphocyte ratio in predicting progression

<bold>Introduction:</bold> The neutrophil-lymphocyte ratio (NLR) is a biomarker involved in the prognosis of several inflammatory pathologies. What about Interstitial lung disease (ILD)? <bold>Aim:</bold> to study the prognostic performance of NLR in predicting progression in ILD. Methods : This is a retrospective study including patients with ILD, hospitalized in Charles Nicolle Hospital’s Pulmonalogy Department in Tunis, between 2000 and 2021. All patients was followed up on at least 1 year. They all had clinic, spirometric and scan control. Patients with idiopathic pulmonary fibrosis (IPF) were not included. The ROC curve of the NLR was generated. Area under the curve (AUC) was measured and cut-off was identified to evaluate sensitivity (Se) and specificity (Sp) in predicting ILD progression. Results : We included 90 patients (52 women), with mean age of 60years. Seventy-seven (85,6%) patients underwent bronchoalveolar lavage fluid (BALF). The median BALF white blood cell count was 330 (×103/ mm3). The median BALF NLR was 1.79 [0.1-11.3]. Median Blood NLR was 4.3 [0.13-14.8]. There wasn’t correlation between blood and BALF NLR (r=0.4). Thirty patients were diagnosed with progressive fibrosing interstitial lung disease (PIF-ILD). BALF NLR was predictive of progression (cut-off: 0.28, AUC 0.62, sensitivity 0.64, specificity 0.65), worsening respiratory symptoms (AUC=0.63, p=0.048), FVC decline>5% (AUC=0.7, p=0.012) and radiological progression (AUC=0.63, p=0.05). Concerning blood NLR, it wasn’t performing in predicting ILD progression (p:0.3, AUC:0.32). <bold>Conclusion:</bold> According to our study, BALF NLR seems to have a prognostic value in progression prediction in ILD out of IPF. Further prospective studies are needed.