Allergen Specificity in Specific IgE Cutoff

To assess the clinical relevance of specific immunoglobulin E (IgE) cutoffs for aeroallergens in children.

The population studied includes 6-year-old Danish children in the Copenhagen Prospective Study on Asthma in Childhood in 2000 and 2010.

The distribution of 5 common aeroallergens (house dust mite [HDM], cat, dog, grass, and birch) were assessed among children in these cohorts at 6 years old. Levels were compared between the entire population studied and children with pediatrician-diagnosed allergic rhinitis.

The median value of specific immunoglobulin E (sIgE) in children varied across groups; all children had a median sIgE of 0.14 (HDM), 0.06 (cat), 0.07 (dog), 0.33 (grass), and 0.2 (birch) kUA/L; symptomatic children with rhinitis had a sIgE of 6.29 (HDM), 1.41 (cat), 5.73 (dog), 2.43 (grass), and 1.97 (birch) kUA/L. In symptomatic children, the median values were higher and had increased variation. There was significant overlap between the 2 sets, with high IgE levels even in some of the asymptomatic children.

A uniform cutoff was not found among the allergens tested that discriminate between symptomatic and asymptomatic individuals.

Currently, there are no established cutoffs for allergen specific IgE levels that distinguish clinical allergy from asymptomatic sensitization. Having clinically relevant cutoffs for specific IgE levels that correlate with clinical symptoms would facilitate interpretation of test results. The authors’ comparison of allergen specific IgE levels in a prospective cohort of children with a subgroup that had pediatrician-diagnosed allergic rhinitis reveals that there is important overlap of IgE levels between the 2 groups. Similar to food and venom allergy, having detectable IgE has not equate to clinical allergy. In this prospective asthma study, Schoos et al should consider the role of a diagnosis of asthma on the clinical relevance of the sensitization noted, when appropriate to make correlations. Further studies will be needed to determine if allergen specific cutoffs can be established for the diagnosis of rhinitis and asthma.