Food and Drug Reactions and Anaphylaxis
Prediction of tolerance on the basis of quantification of egg white-specific IgE antibodies in children with egg allergy☆,☆☆

https://doi.org/10.1067/mai.2002.126081Get rights and content

Abstract

Background: It is thought that the natural evolution of food allergy has a good tolerance prognosis. However, there are few follow-up studies that determine the exact probability of tolerance to a given food or that analyze prognostic factors that can help us to understand the evolution of a child who begins life with a food allergy. Objective: We sought to determine the likelihood that children younger than 2 years of age with allergy to egg would eventually have tolerance to it and to analyze several prognostic predictors using egg white-specific IgE level as the main variable. Methods: We performed a prospective study of 58 children younger than 2 years of age with egg allergy, who were studied periodically until tolerance developed or until the end of the study. During the follow-up period, open challenge tests were carried out according to previously established criteria to verify tolerance to egg. Factors such as egg white-specific IgE level, serum total IgE level, symptoms after egg ingestion, size of skin prick test reactions to egg white, atopic dermatitis, and sex were analyzed as prognostic markers. Kaplan-Meier survival curves were used to calculate cumulative tolerance probability. Predictor influence and relative prognostic importance were estimated with the Cox proportional regression model. Results: The median time from the appearance of the first symptoms to tolerance was 35 months. Cumulative tolerance probability was 16% at 12 months of follow-up, 28% at 24 months, 52% at 36 months, 57% at 48 months, and 66% at 60 months. The relative weight of prognostic factors, expressed as the hazard ratio, was 50.95 for symptoms and 3.74 for the size of skin prick test reactions, with both being independent effects. The hazard ratio was 1.173 for every 0.1-unit decrease in the concentration log (decimal logarithm) of specific IgE level, with this effect being associated with tolerance only in children with cutaneous symptoms. Conclusions: Half of the children younger than 2 years of age with egg allergy will tolerate the food at 35 months of follow-up, and the proportion could be 66% after 5 years. At that age, the main predictors were the symptoms experienced after egg ingestion, followed by the size of skin prick test reactions. In addition, the specific IgE antibody level is an important prognostic marker in children who only had cutaneous symptoms. (J Allergy Clin Immunol 2002;110:304-9.)

Section snippets

Study population

This is a prospective follow-up study of 58 children, 36 boys and 22 girls with a mean age of 16 months (range, 11-24 months), who were given a diagnosis of egg allergy in our outpatient allergy unit according to previously established criteria.11 Briefly, children evaluated in our allergy clinic for immediate hypersensitivity reactions after the ingestion of an egg were included in the study. Inclusion was performed consecutively. At the time of the first visit, skin prick tests and total and

Results

The follow-up time ranged from 7 to 86 months, with a median of 32 months. The median serum total IgE level was 43.5 KUA/L (range, 3-597 KUA/L). The median skin prick test reaction size with egg white, as assessed on the basis of mean wheal diameter, was 6 mm (range, 2.5-16.5 mm). Twenty-nine (50%) children had atopic dermatitis.

A total of 94 challenge tests, 35 at the onset of the study to establish the diagnosis and the remaining 59 during follow-up, were performed. The result was positive in

Discussion

The prognosis of food allergy is considered good because it is thought that most children will outgrow the problem as they become older. However, there are few long-term follow-up studies that show tolerance data at different moments of evolution or that analyze prognostic factors (ie, factors that help us to predict the future of a child allergic to a given food).

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☆

accepted for publication •••.

☆☆

Reprint requests: Mª Teresa Boyano Martínez, C/Ginzo de Limia 55, 9°C, 28034 Madrid, Spain.

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