523 - Not Just Bronchiolitis: Emergency Department Clues to Early Childhood Asthma

Publication Number: 2508.523

Andrea Rivera-Sepulveda, Nemours Children's Hospital, ORLANDO, FL, United States; Christian S. LeFevre, University of Central Florida College of Medicine, Orlando, FL, United States; Anna Jurlina, University of Washington School of Medicine, Seattle, WA, United States; Matthew M. Davis, Nemours Children's Health, Wilmington, DE, United States

Background: Bronchiolitis is a heterogeneous syndrome that can present as classic bronchiolitis, a wheezing-associated viral illness, or early childhood asthma. Distinguishing these at presentation could enable targeted therapy, counseling, and improve lung function outcomes.

Objective: (1) Identify index ED characteristics associated with subsequent asthma after bronchiolitis; (2) time-to-asthma; (3) define an ED "asthma-like" bronchiolitis phenotype.

Design/Methods: We conducted a retrospective cohort study of 1,339 unique ED bronchiolitis visits (2018-2023). Data included demographics, atopy, family history, prior wheeze, exam/severity (peripheral oxygenation [SpO₂], work of breathing, hospitalization), viral testing (respiratory syncytial virus [RSV], rhinovirus [RV]), ED bronchodilator/steroid use, and final diagnoses. Outcomes were: (a) later asthma in the electronic health record; (b) time from index visit to asthma (Kaplan-Meier, Cox); and (c) an asthma-like phenotype defined as ≥1 of: prior wheeze, ED bronchodilator/steroid use, documented atopy/family atopy, wheeze on exam, or bronchodilator/steroid prescription. Group comparisons used χ² or Mann-Whitney. Survival curves were compared with log-rank where groups existed.

Results: Overall, 498/1,339 (37%) children were later diagnosed with asthma. Children who became asthmatic were older, more often male, and more likely to have atopy, prior wheeze, higher ED acuity, wheeze/retractions, and admission (all p< 0.01). Overall, the Kaplan-Meier curve showed a rapid accrual of asthma: asthma-free survival at 24 months was 0.267 (73.3% with asthma by 24 months). Prior wheeze markedly shifted risk (84.1% vs. 71.6% asthma at 24 months; log-rank p=0.008). RV bronchiolitis had the highest 24-month asthma proportion (84%) vs. RSV (20.9%), although the 4-group comparison (vs. flu/hMPV/PIV/Adenovirus vs. no testing) was not significant (p=0.410). At the index ED visit, 748/1,339 (55.9%) met criteria for an asthma-like phenotype. RV-positive children were more often asthma-like than RV-negative children (70.1% vs 54.5%; χ²=10.5, p=0.001). In multivariable models, prior wheeze, atopy, RV, and obstructive findings were associated with earlier asthma; classic hypoxic RSV resembled non-asthmatic bronchiolitis.

Conclusion(s): In this cohort, over half of ED bronchiolitis visits already displayed an asthma-like pattern, and those children went on to asthma sooner. A pragmatic ED set of features, prior wheeze/atopy plus obstructive exam and RV, may help flag bronchiolitis encounters that represent early asthma, but this rule requires validation before clinical deployment.

Table 1. Demographics and selected clinical characteristics of the cohort.
Notes: Values shown as n (%) unless specified. p-values from χ² or Mann-Whitney, as appropriate. Table shows that children who later developed asthma already had more airway/atopic features and a different viral pattern at the index visit.

Figure 1. Kaplan-Meier curves for time to asthma after ED bronchiolitis, by prior wheeze.
Time from index bronchiolitis ED visit to first asthma diagnosis. Children with documented prior wheeze had a markedly lower asthma-free survival at 24 months (0.159 → 84.1% with asthma) compared with those without prior wheeze (0.284 → 71.6% with asthma); log-rank p = 0.008.

Figure 2. Asthma-like ED bronchiolitis phenotype by viral etiology
Figure 2. Proportion of ED bronchiolitis encounters classified as asthma-like (defined as ≥1 of: prior wheeze, ED bronchodilator or systemic steroid, airway/wheeze/RAD ED diagnosis, or atopy history) by viral etiology. Children with rhinovirus/enterovirus were more often asthma-like than those with RSV (50.2% vs 45.5%; χ²=10.5, p=0.001), supporting an RV-triggered, asthma-prone bronchiolitis phenotype.