AUTHOR=Jin Lei , Guo Jie , Deng Keting , Yao Yang 

TITLE=Neutrophil-to-lymphocyte ratio as a biomarker for asthma identification and severity stratification: a systematic review and meta-analysis

JOURNAL=Frontiers in Medicine

VOLUME=Volume 12 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2025.1620695

DOI=10.3389/fmed.2025.1620695

ISSN=2296-858X

ABSTRACT=BackgroundReliable biomarkers for asthma identification and severity stratification remain lacking. The neutrophil-to-lymphocyte ratio (NLR) has emerged as a potential candidate, but evidence remains inconsistent. This study evaluates the value of NLR in distinguishing asthma patients from healthy controls and its correlation with disease severity.MethodsA systematically search was conducted across PubMed, Embase and Web of Science for studies reporting NLR levels in asthma patients and healthy controls. Pooled mean differences (MD) and 95% confidence intervals (CIs) were calculated using random-effects models. Receiver operating characteristic (ROC) curves assessed discriminative performance.ResultsNineteen studies (43,164 patients, 8,411 controls) were included. When comparing across different asthma severities, the NLR showed incremental increases across severity: mild vs. moderate asthma (MD = −0.41, 95% CI: −0.64 to −0.18, p = 0.0005), mild vs. severe (MD = −3.10, 95% CI: −6.26 to 0.06, p = 0.05), and moderate asthma vs. severe asthma (MD = −2.44, 95% CI: −5.31 to 0.44, p = 0.10). The comparison between severe and non-severe asthma also showed a significant difference (MD = −2.06, p < 0.0001). NLR robustly discriminated asthma from controls (AUC = 0.929) and severe from non-severe asthma (AUC = 0.914). Subgroup analyses revealed higher NLR differences in pediatric populations and developed regions.ConclusionNLR is a promising biomarker for asthma and severity stratification, although its discriminative ability between moderate and severe stages is limited. Future studies should explore its role in predicting asthma progression and exacerbations.