From evidence to practice: A systematic review-based diagnostic algorithm for paediatric eosinophilia across socioeconomic context.

AIM: Paediatric eosinophilia is a common clinical dilemma, often leading to resource- and time-consuming assessments. We aim to evaluate the main aetiologies of eosinophilia in children from different socioeconomic settings and propose a diagnostic algorithm.

METHODS: A systematic literature review was conducted through PubMed, Embase and the Cochrane Library. Studies published from January 2012 to June 2023 reporting the incidence and aetiology of peripheral eosinophilia in children were included. Evidence from studies on children originating from low- or high-income countries was compared.

RESULTS: A total of 15 observational studies, encompassing 3409 children, were included. The causes of eosinophilia varied based on the children's origin and the eosinophilia severity. In children from high-income countries, allergic diseases were the leading cause, with a prevalence of 7.7%-78.2%, while parasitosis ranged from 1.0% to 9.1%. In children from low-income countries, parasitosis was predominant, ranging from 17.7% to 88.3%, although allergic diseases were found in 2.5%-4.8% of cases. Concerning severity, allergic diseases were the leading cause of mild-to-moderate eosinophilia; parasitosis was associated with moderate-to-severe eosinophilia, while immunological disorders were mostly found in severe cases.

CONCLUSION: We developed a step-up diagnostic algorithm that considers the child's origin and eosinophilia severity and could optimise resource allocation.