Clinical Outcomes Associated With Long‐Acting Beta Agonist Escalation in Preschool Children With Severe Asthma: A Retrospective Hospital Based Clinic Cohort Study

BACKGROUND: We define adherent, difficult-to-treat asthma as 'true severe asthma.' In preschool children, evidence for add-on long-acting beta-agonists (LABA) to inhaled corticosteroids (ICS) in those with persistent uncontrolled disease despite high-dose ICS remains limited. We evaluated clinical outcomes of ICS-LABA therapy in this population. METHODS: This retrospective observational study (2021-2024) included children aged 6-72 months with severe, uncontrolled asthma despite medium- to high-dose ICS and verified adherence, who were initiated on LABA therapy. Primary outcomes were severe exacerbations (systemic corticosteroid use, hospitalizations, and uncontrolled symptoms). Secondary outcomes included PICU admissions and spontaneously reported adverse events. Outcomes 6 months before and after LABA initiation were compared using generalized estimating equations (GEE), adjusting for seasonality, age, sex, and atopy. RESULTS: Fifty-three children were included (mean age 38.8 ± 17.6 months, 41.5% male, atopy 49.1%). LABA initiation was associated with a substantial reduction in clinical burden: hospitalizations declined from 41.5% to 3.8% (p < 0.001), systemic corticosteroid use from 86.8% to 52.8% (p < 0.001), and daily symptoms from 86.8% to 37.7% (p < 0.001). PICU admissions decreased from 9.4% to 0%. These associations remained significant after adjustment for covariates (p < 0.001). No adverse events were spontaneously reported by patients or caregivers during the follow-up period; however, systematic adverse event surveillance was not conducted. CONCLUSION: In adherent preschool children with true severe asthma, LABA initiation was associated with observed improvements in clinical outcomes. Still, prospective controlled studies with systematic safety surveillance are warranted.