Multi-center evaluation of baseline neutrophil:lymphocyte (NLR) ratio as an independent predictor of mortality and clinical risk stratifier in Idiopathic Pulmonary Fibrosis

Summary Background Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal disorder with a variable disease trajectory. The aim of this study was to assess the potential of neutrophil-to-lymphocyte ratio (NLR) to predict outcomes for people with IPF. Method We adopted a two-stage discovery and validation design using patients from the UCL partners (UCLp) cohort. For the discovery analysis, we included 71 patients from UCLH. In the validation analysis, we included 928 people with IPF, using real-life data from UCLH and 5 other UK centres. Data were collected from patients presenting over a 13-year period with a mean follow up time of 3.7 years. Findings In the discovery analysis, we showed that values of NLR (/=2.9) were associated with increased risk of mortality (HR 2.04, 95% CI 1.09-3.81; p=0.025). In the validation cohort we confirmed this association of high NLR with mortality (HR 1.65, 95% CI 1.39-1.95; p<0·0001) and showed incorporation of baseline NLR in a modified GAP-stage/index (GAP/index)-plus improved predictive ability Interpretation We have identified NLR as a widely available test that significantly correlates with lung function, can predict outcomes in IPF and refines clinical GAP-staging. NLR may help ILD specialist centres prioritise at risk patients in a timely way, even in the absence of lung function.