The role of eosinophils in the management of acute paediatric wheeze: a scoping review

Acute wheeze is one of the most common paediatric presentations to emergency care. Although blood eosinophils (BEO) are an established biomarker of type 2 inflammation in stable asthma, their role in guiding acute management—particularly systemic corticosteroid use—remains unclear. The aim of this review was to map and synthesise the existing evidence on the measurement and clinical utility of BEO sampled during acute wheeze exacerbations in children. A scoping review was conducted in accordance with Joanna Briggs Institute methodology and Preferred Reporting Items for Systematic Reviews and Meta-Analysis extension for scoping reviews (PRISMA-ScR) guidelines. Medline, Embase, Cochrane Library and Web of Science were searched for studies published in the last 20 years involving children under 16 years presenting acutely with wheeze and undergoing eosinophil testing. Prospective and retrospective studies were included. Data were summarised descriptively according to eosinophil measurement methods, reported values, cut-offs and associations with characteristics and treatment response. Eight heterogeneous studies (n = 855) met inclusion criteria, comprising five observational or retrospective studies and three randomised controlled trials. BEO reporting varied widely, with inconsistent units, cut-offs and poorly described sampling timing. No study utilised point-of-care testing. Across studies, eosinophil dynamics differed by age, wheeze phenotype, disease severity and viral aetiology, preventing meaningful comparison. Evidence supporting eosinophil-guided corticosteroid use was limited. Two studies demonstrated improved outcomes with systemic corticosteroids in children with rhinovirus-associated wheeze and higher BEO, while lower BEO were observed in respiratory syncytial virus (RSV)-associated wheeze. There is a paucity of high-quality data describing BEO during acute wheeze exacerbations in children. Current evidence underpinning eosinophil-guided care is largely derived from stable outpatient cohorts and may not be directly applicable to acute settings. Prospective studies with standardised sampling of BEO during acute presentations are needed to inform precision-based corticosteroid use.