Patients and methods
Preschool children aged 3-6 years who attended between 01.05.2022 and 30.11.2022 the Division of Paediatric Allergy, Pulmonology and Cystic Fibrosis of the University Hospital in Frankfurt with suspected asthma were retrospectively analysed.
All children had a history of recurrent episodes of physician-documented wheezing, cough and/or respiratory distress with bronchodilator responsiveness of which at least one episode in the last 12 months. Furthermore, they were free from respiratory tract infections for ≥2 weeks prior to the measurements.
Atopy in children was defined as a positive skin prick test (SPT) > 3 mm against common allergens (birch, grass, house dust mites, cat, milk and egg).
Patients receiving SABA and LABA, in the last 6 and 24 hours respectively, were excluded as well as those suffering from chronic disease or infections affecting the respiratory system (e.g., congenital heart disease, cystic fibrosis, bronchopulmonary dysplasia, tuberculosis, HIV).
Ethics approval was obtained from the ethics committee of the Goethe University in Frankfurt (Application Number 2022-1094). According to the German Federal Data Protection Act (BDSG) there is no right to information under article 15 of regulation (EU) 2016/679, as the data is required for scientific research purposes and providing the information would require a disproportionate effort.