The Prognostic Value of Baseline Neutrophil-to-Lymphocyte Ratio for Mortality in Idiopathic Pulmonary Fibrosis: A Systematic Review and Meta-Analysis

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrosing pulmonary disease with an unfavorable prognosis. It usually occurs in the older age group and shows an extremely variable clinical course. Neutrophil-to-lymphocyte ratio (NLR) is an affordable, widely accessible blood-based biomarker that has great potential for evaluating disease outcomes. Therefore, this systematic review and meta-analysis aim to synthesize the existing literature and analyze the prognostic value of baseline NLR for mortality in IPF patients. Literature was retrieved from PubMed, Web of Science, Embase, and ScienceDirect from the earliest available records to April 2026. Studies investigating the prognostic role of baseline NLR in IPF patients and reporting mortality outcomes with HRs were included. Random-effects (RE) and fixed-effects (FE) models were used to pool HRs. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of included studies. This meta-analysis included four retrospective cohort studies comprising 1,524 IPF patients. All studies demonstrated good quality (NOS 8/9). Pooled analysis indicated that increased baseline NLR was related to increased mortality risk (pooled HR = 1.54, 95% CI 0.90-2.64, p = 0.083), although statistical significance was not reached under the RE model. The FE model was used as a sensitivity check, yielding a similar direction of association (HR 1.43, 95% CI 1.21-1.68), although the RE model was prioritized due to observed heterogeneity. Furthermore, a supplementary exploratory analysis demonstrated a pooled HR of 1.67 (95% CI 1.12-2.49) under the RE model, with the association remaining in the same direction as the primary analysis. However, these analyses were exploratory, and findings should be interpreted with caution as they combine adjusted and unadjusted estimates. The leave-one-out sensitivity analysis further supported the stability of our pooled results. This systematic review and meta-analysis suggest that an elevated baseline NLR is associated with a nonsignificant trend toward increased mortality risk in IPF patients, as the primary RE model did not reach statistical significance. Prospective multicenter studies with standardized NLR cutoff thresholds are needed to verify its clinical application.