Allergy-Related Symptoms Are Poorly Predicted by IgE and Skin Prick Testing in Early Life

Introduction: In childhood, the so-called allergic march involves progression from IgE sensitization to allergy-related symptoms. Both IgE sensitization and relevant clinical symptoms are required for the diagnosis of allergy, but concordance between test results and clinical symptoms varies greatly, creating challenges for the diagnostics and for the prediction of outcomes. We assessed the prevalence of IgE sensitization and allergy symptoms, concordance between 2 IgE sensitization testing methods, and predictive value of these tests in relation to clinical symptoms in young Finnish children. Methods: The current study included 2 series of children: a birth cohort, in which the participants were followed prospectively from birth up to 3 years, and a young children cohort observed from 3 to 5 years of age. They were regularly monitored for sensitization by measuring serum allergen-specific IgEs (sIgEs) and performing skin prick tests (SPTs). The emergence of atopic dermatitis, wheezing, and symptoms associated with food allergies was recorded. Results: Over the first 5 years of life, the prevalence of sIgE sensitization was 46%, while it was 36% for positive SPTs. Disease prevalence was 26% for atopic dermatitis, 25% for wheezing, and 19% for symptoms associated with food allergies. Concordance between sIgE and SPT results was good for aeroallergens, but poor for dietary allergens. The association between clinical symptoms and sensitization was stronger at 5 years than at 3 years of age. The proportion of children with concordant combinations of allergy symptoms and sensitization markers in contrast to those with discordant combinations increased from 3 to 5 years. Conclusion: In early childhood, testing for IgE sensitization predicts allergy-related symptoms in an age-dependent manner, but not particularly well. Tests predict symptoms caused by aeroallergens clearly better than those caused by dietary allergens. The clinical relevance of sensitization testing in early life is therefore limited in the prediction of true allergy.