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Original Article

Nonlinear association between neutrophil-to-lymphocyte ratio and asthma in children and adolescents in the USA: a cross-sectional study

Chuhan Cheng^1,2,3  , Liyan Zhang^1,2,3

¹Fujian Medical University, Fuzhou, China
²Fuzhou Children's Hospital of Fujian Medical University, Fuzhou, China
³Fuzhou First General Hospital Affiliated with Fujian Medical University, Fuzhou, Korea

Correspondence Chuhan Cheng ,Email: chcheng@fjmu.edu.cn

Received: December 4, 2024; Revised: February 21, 2025   Accepted: February 21, 2025.

Abstract

Background
The neutrophil-to-lymphocyte ratio (NLR) is a marker of systemic inflammation associated with various diseases including respiratory conditions. However, the relationship between NLR and asthma in the pediatric population remains underexplored.
Purpose
This study aimed to explore the association between NLR and asthma in children and adolescents and assess its potential role as a predictive biomarker for pediatric asthma.
Methods
We retrospectively analyzed the medical records of 12,974 children and adolescents from the National Health and Nutrition Examination Survey in 2011-2020. NLR was defined as the ratio of neutrophil to lymphocyte counts. Asthma was diagnosed using a structured questionnaire. Multivariate logistic regression models were used to evaluate the association between NLR and asthma. A restricted cubic spline was used to explore non-linear relationships, and a threshold analysis was conducted to identify potential cutoff values for the NLR.
Results
A total of 12,974 children and adolescents were included (male: 6,686 [51.5%]; mean age: 10 years [IQR, 5.0–14.0]). After the adjustment for confounders, participants with the highest versus lowest NLR exhibited a significantly elevated risk of asthma (odds ratio [OR]=1.39; 95% confidence interval [CI], 1.13–1.71). Additionally, a multivariate restricted cubic spline analysis revealed a non-linear relationship between NLR and asthma (p=0.023). A threshold analysis revealed that an NLR<2.23 was significantly associated with an increased risk of asthma (OR=1.23; 95% CI, 1.05–1.45), while an NLR≥2.23 showed no significant association. A subgroup analysis revealed no interactive role of NLR and asthma.
Conclusion
Our findings indicate a non-linear saturation-effect relationship between NLR and asthma in children and adolescents.

Keywords :Neutrophil; Lymphocyte; Asthma; Children; Adolescent