Sensitization pattern to inhalant and food allergens in symptomatic children at first evaluation

Abstract

Background: Data on specific IgE sensitization prevalence in children with allergy-like symptoms seen in the primary care setting are rare. Early diagnosis of allergic diseases is important to prevent clinical manifestations, exacerbations or expansion of allergic diseases to other organ systems. The present study aims to assess the usefulness of early serological diagnosis in children with common allergic symptoms.

Methods: 532 children (<15 years of age), with at least one of ten allergy-like symptoms, from 21 primary care centers in two geographic areas of Italy and Spain were included in the study. Patients were tested with, either Phadiatop® Infant (0-5 years of age) or Phadiatop® and food mix (fx5e) (>5 years of age) to discriminate atopic from non-atopic subjects. A blood sample of atopic subjects was taken for additional 6-26 specific IgE antibody determinations from a predefined panel using the ImmunoCAP® System.

Results: 267 children (50.2 %) were positive in the initial test and were classified as atopic. 14 % were mono-sensitized, 37 % were sensitized to 2-3 allergens and 49 % to more than 3 allergens. The average number of symptoms in the atopic group was 3.3 vs 2.8 in the non-atopic group. The prevalence of sensitization to single allergens was highest for grass and ragweed pollen and house-dust mites (19-28 %). Sensitization to tree allergens was highest for olive tree (16.5 %). Cow's milk and egg white were the most sensitizing foods (~15 %). Food allergen sensitization predominated in younger children (OR = 2.8) whereas the inverse occurred with inhalant allergens (OR = 2.5 to 5.6). A significant positive correlation between patient age and the number of sensitizations was found.

Conclusions: Specific IgE sensitization in children with allergy-like symptoms is common. Multiple sensitization is predominating. Number of clinical symptoms was higher in the atopic group compared to the non-atopic without a correlation with the number of positive allergens. Age seems to play a crucial role in the development of sensitization with a significant positive correlation between patient age and the number of sensitizations.

Fig. 1

Number of allergen sensitizations in regard to number allergy-ike symptoms recorded. Boxes include median (line) and mean (+) values and the interquartile range (25-75 %). Whiskers extend to most extreme data points. Spearman Correlation Coefficient, r = 0.01517; p = 0.8117 (ns). n is the number of patients, * includes 2 patients with 8 symptoms

Fig. 2

sIgE sensitization levels (kUA/L) of positive samples in correlation to the prevalence of sensitization. Left Y-axis: Boxes include median (line) and the interquartile range (25-75 % observation). Whiskers extend to the most extreme data points. Right Y-axis: Black dots shows the prevalence for the allergens

Fig. 3

Patients profile in seven groups of selected allergens. Proportions of negative results, mono sensitization and multiple sensitizations as well as the most frequent sensitization profile are reported. Within brackets number of observations and mean number of positives results are given. See Tables 1 and 2 under Group/cluster for allergens included, indicated with X

Fig. 4

Sensitization development and patient’s age. Number of positive observations with the cut-off over 0.35 kUA/L correlated with the patients age; * allergens that are not included in the OR since these sIgE tests were only performed in children <5 years of age)

Fig. 5

Relationship between multiple sensitization and patient’s age. Median and interquartile range (25-75 %) of sensitizations in 63 (1–3 years of age) and 186 (4–15) children respectively. Whiskers extend to the 10–90 percentile. p < 0.01 (Mann Whitney test)