Longitudinal FeNO monitoring in pediatric asthma: association of FeNO and its trajectory patterns with asthma control status

BACKGROUND: Fractional exhaled nitric oxide (FeNO) is a non-invasive biomarker of type 2 inflammation with potential for personalized asthma management. However, the longitudinal patterns of FeNO and their association with childhood asthma control remain insufficiently characterized. METHODS: This cohort study enrolled children with newly diagnosed asthma from Shanghai Children's Medical Center. Participants underwent baseline assessments and serial FeNO measurements at diagnosis and at 3-month intervals over 12 months. Asthma control was assessed at 12 months using Global Initiative for Asthma (GINA) criteria. Longitudinal trajectories of FeNO were identified using group-based trajectory modeling (GBTM). Associations of time-specific FeNO levels and FeNO trajectory group with uncontrolled asthma at 12 months were analyzed using logistic regression. RESULTS: Among 142 children (mean age 6.92 ± 2.08 years; 71.1% male), 125 (88.0%) achieved controlled asthma and 17 (12.0%) had uncontrolled asthma at 12 months. Elevated FeNO at 3 and 12 months was significantly associated with increased odds of uncontrolled asthma after adjusting for covariates. Longitudinal FeNO levels showed two distinct trajectories: low-stable (80.3% of participants) and high-rising (19.7%). Compared with the low-stable group, the high-rising group had significantly older age, later wheezing onset, higher serum total immunoglobulin E (IgE) and eosinophil percentages (all p < 0.05). Children in the high-rising trajectory group had higher odds of uncontrolled asthma (OR = 5.86; 95% CI: 1.28-29.57; p = 0.025). CONCLUSIONS: Elevated FeNO levels during follow-up and a high-rising FeNO trajectory are associated with uncontrolled asthma at 12 months in children with newly diagnosed asthma. Longitudinal FeNO monitoring may help identify children at increased risk of poor asthma control and support more individualized asthma management.