Eosinophil cationic protein (ECP) in schoolchildren living in a mountainous area of Norway: a population‐based study of ECP as a tool for diagnosing asthma in children with reference values

Background: Most previous studies on eosinophil cationic protein (ECP) have been performed on carefully selected groups of asthmatic patients. Few studies based upon population cohorts have been reported. The primary objective of the present study was to assess the usefulness of serum eosinophil cationic protein (s‐ECP) in the diagnosis of asthma in schoolchildren and determine reference values based on measurements in healthy children. Methods: The population consisted of 216 schoolchildren (aged 7–16 years) who in a previous questionnaire had reported asthma or asthma‐like symptoms and a control group. The questionnaire study comprised the entire population of schoolchildren in Upper Hallingdal. After clinical assessment, blood samples, and skin prick tests, these subjects were then reclassified into four groups: atopic and nonatopic asthmatic and nonasthmatics. S‐ECP was assessed in relation to atopy, asthma severity, allergen exposure, and sex. Results: The asthma group (n=105) had significantly higher mean s‐ECP level than the nonasthma group (n=111) (13.3 vs 8.3 µg/l, P