Allergen Sensitization Patterns and FeNO-Defined Type 2 Inflammatory Phenotype in Children with Asthma: A Real-World Retrospective Study

Background: Allergen sensitization is common in pediatric asthma, but its relationship with inflammatory phenotypes and acute clinical events remains incompletely characterized in real-world practice. Objective: To describe allergen sensitization patterns in children with asthma and evaluate their association with fractional exhaled nitric oxide (FeNO)-defined type 2 inflammatory phenotype, with acute exacerbation and abnormal lung function records as exploratory outcomes. Methods: This single-center retrospective real-world study included children recorded in an asthma monitoring database from January 2025 to May 2026. The primary analysis used the earliest visit after patient-level deduplication. Sensitization patterns were classified as any allergen, inhalant allergen, food allergen, multiple sensitization, and high-grade sensitization. Elevated FeNO was defined as FeNO >35 ppb. Complete-case analysis was performed for multivariable models. Group comparisons, false discovery rate correction, trend tests, Spearman correlation, and multivariable logistic regression were used. Results: Among 812 unique children, 396 (48.8%) had FeNO records. Inhalant allergen sensitization predominated, and dust mite was the most common sensitization category. Pollen sensitization and multiple sensitization increased across FeNO strata. The multivariable model included 393 complete cases and 51 events. Pollen sensitization (adjusted odds ratio [aOR], 2.56; 95% confidence interval [CI], 1.22–5.35) and multiple sensitization (aOR, 2.14; 95% CI, 1.11–4.12) were independently associated with FeNO > 35 ppb. The FeNO model showed acceptable discrimination (area under the curve, 0.761), good calibration by the Hosmer–Lemeshow test ( P = 0.773), and Nagelkerke R 2 of 0.162. Adding pollen and multiple sensitization to a clinical baseline model modestly improved prediction (Delta AUC, 0.027; continuous net reclassification improvement, 0.334), whereas integrated discrimination improvement (IDI) was not statistically significant. No stable independent association was observed between specific allergen categories and acute exacerbation or abnormal lung function records. Conclusion: In children with asthma, allergen sensitization patterns were more closely associated with FeNO-defined type 2 inflammatory phenotype than with acute clinical events. Combined FeNO and allergen assessment may support phenotype-oriented assessment.