Exhaled biomarkers and gene expression at preschool age improve asthma prediction at 6 years of age.

Rationale: A reliable asthma diagnosis is difficult in wheezing preschool children.Objectives: To assess whether exhaled biomarkers, expression of inflammation genes, and early lung function measurements can improve a reliable asthma prediction in preschool wheezing children.Methods: Two hundred two preschool recurrent wheezers (aged 2–4 yr) were prospectively followed up until 6 years of age. At 6 years of age, a diagnosis (asthma or transient wheeze) was based on symptoms, lung function, and asthma medication use. The added predictive value (area under the receiver operating characteristic curve [AUC]) of biomarkers to clinical information (assessed with the Asthma Predictive Index [API]) assessed at preschool age in diagnosing asthma at 6 years of age was determined with a validation set. Biomarkers in exhaled breath condensate, exhaled volatile organic compounds (VOCs), gene expression, and airway resistance were measured.Measurements and Main Results: At 6 years of age, 198 children were diagnosed (7...