Study participants
We analyzed the data from children who had undergone the MCC at the Department of Pediatric Allergy at the Children’s Hospital, University of Bonn between January 2009 and December 2018. From an initial population of 939 children, patients with an obstructive pattern, that is baseline forced expiratory volume in one second (FEV1) and/or FEV1/forced vital capacity (FVC) ratio < 80% predicted, or relevant (≥200 mL or ≥12%) reversibility in executed spirometry (n = 712), were not included. Furthermore, according to the established protocol in our department, children with primarily exercise-induced symptoms underwent exercise challenge testing before the MCC and those children who had exercise-induced bronchoconstriction in the exercise challenge testing were also excluded (n = 104). The data from 123 children were analyzed (Fig.1).