Factors Associated With Asthma Diagnosis Within Five Years of a Bronchiolitis Hospitalization: A Retrospective Cohort Study in a High Asthma Prevalence Population

Abstract

OBJECTIVES: Bronchiolitis, the leading cause of infant hospitalizations in the United States, is associated with increased risk of childhood asthma. We hypothesized that factors during a bronchiolitis hospitalization were associated with subsequent asthma. METHODS: This is a retrospective cohort study at an urban, tertiary-care children’s hospital of infants <12 months old, hospitalized for bronchiolitis. The primary outcome measure was an asthma diagnosis, defined as a billing code for an asthma visit or a prescription for controller medication, within 5 years of discharge from the bronchiolitis hospitalization. RESULTS: There were 534 infants hospitalized for bronchiolitis, of which 294 (55.1%) were diagnosed with asthma, and 102 (19.1%) were hospitalized for asthma within 5 years of discharge. There was significant interaction between age and family history. In both models, female sex was protective (odds ratio [OR] 0.46). Age and race were only associated with asthma in infants without a family history of asthma: age (OR 1.19; 95% confidence interval 1.08–1.32) and race (OR 4.06; 95% confidence interval 1.56–10.58). Hospitalization length, ICU stay, albuterol treatments received, supplemental oxygen, respiratory support, highest respiratory rate, and respiratory syncytial virus infection were not associated with asthma diagnosis. CONCLUSIONS: More than 55% of infants hospitalized for bronchiolitis developed asthma within 5 years of discharge. Demographic and family history variables were independently associated with asthma. However, hospital-based variables during the bronchiolitis hospitalization were not independently associated with asthma. These results can direct further research and differentiate anticipatory guidance for infants with bronchiolitis at risk for asthma.