(873) Adjunctive Azithromycin for Acute Viral Bronchiolitis: A Single-Center Retrospective Cohort Study

Introduction: Adjunctive azithromycin (AZI) for asthma has been described but limited data supports its use in other inflammatory conditions such as bronchiolitis. We sought to determine if differences exist in patient characteristics and clinical outcomes for critically ill children hospitalized for bronchiolitis with and without exposure to AZI.

Methods: We performed a single-center, retrospective cohort study including children 0-3 years of age admitted to a 28-bed pediatric intensive care unit (PICU) for bronchiolitis from Oct 2020 - Feb 2023. We excluded for alternative AZI indications (e.g., pertussis and atypical pneumonia). Primary outcomes were descriptive including demographics, anthropometrics, PICU severity of illness indices, comorbidities, viral testing results, clinical interventions (i.e., systemic corticosteroids, continuous nebulized albuterol, non-invasive ventilation, and invasive ventilation), length of stay (LOS) and in-hospital mortality. Statistics were descriptive (i.e., means, medians, and proportions) and comparative (Fisher’s exact, student’s t, and Wilcoxon rank-sum tests) where appropriate.

Results: Of the 257 children studied, 12 (3.8%) were given AZI at 10mg/kg/dose for 3 days. Treatment with AZI was initiated at a median of 0.7 (interquartile range [IQR]: 0.2,1.9) days after hospitalization. No detectable differences in age, gender, weight, race, ethnicity, Pediatric Risk of Mortality-3 Probability of Death, or rate of concurrent bacterial infections were observed for those with and without AZI exposure. Compared to those not prescribed AZI, those with adjunctive AZI were more frequently premature (50% vs 15.1%, p=0.007), tested positive for multiple viruses (mean of 1.4±0.9 vs 1±0.6, p=0.018), experienced a longer median PICU LOS (4 [IQR:2.8,7.1] vs 2.1 [IQR:1.5,3.6], p=0.006), and more frequently were treated for bronchospasm including systemic corticosteroids (91.7% vs 52.6%, p=0.007) and continuous albuterol (66.7% vs 21.6%, p=0.001). No differences in invasive ventilation, non-invasive ventilation, or mortality rates were noted.

Conclusions: In this single center report, children prescribed adjunctive AZI for acute bronchiolitis was rare (3.8%) and more commonly among those with a history of prematurity and active treatment for bronchospasm / reactive airway disease.