Asthma is the most common chronic disease in children. Advances in knowledge of asthma pathophysiology have led to the description of endotypes including: allergic eosinophilic asthma, non-allergic eosinophilic asthma (grouped under the term T2-high) and neutrophilic asthma (T2-low). Eosinophilic asthma is poorly described in children, and clinical practice suggests an increase in its prevalence over time. The aim of our study was to evaluate the evolution of the proportion of hyper-eosinophilic asthma in the pediatric population over time, and to characterize this population.

We conducted a single-center retrospective study at the University Hospital of Rouen, France, between 1995 and 2021: 1041 children aged 0–17 years, followed for asthma in our tertiary center, in which eosinophil blood count was prescribed, were included.

Between 1995 and 2021, we found no change in hyper-eosinophilia levels in asthmatic children. We found that blood eosinophilia > 400 cells/μL was associated with allergy, male gender and the 6–11 age group. Biologic therapies were significantly associated with hyper-eosinophilia (p < 0.001).

Our results suggest that we repeat more eosinophilia assays during follow-up of an asthmatic patient, giving the clinical impression of higher hyper-eosinophilia. The three biologic therapies currently approved for young children target T2-high asthma. A new monoclonal antibody targeting TSLP is available in children over 12 years old; it is effective in T2-low asthma, according to initial studies. This would be an interesting prospect for young children with severe T2-low, for whom no biotherapy is currently available.