Food Allergy in Infants With Atopic Dermatitis: Limitations of Food-Specific IgE Measurements

Abstract

BACKGROUND AND OBJECTIVES: Children with atopic dermatitis (AD) have a higher risk for development of food allergies. The objective of this study was to examine incidence of food allergy development in infants with AD and the predictive value of food-antigen-specific immunoglobulin E measurements.METHODS: This trial examined the long-term safety and efficacy of pimecrolimus cream 1% in .1000 infants (3-18 months) with mild-to-severe AD without a history of food allergy. Food allergy development was followed throughout a 36-month randomized double-blind phase followed by an open-label (OL) phase up to 33 months. Additionally, sIgE for cow's milk, egg white, peanut, wheat, seafood mix, and soybean was measured by ImmunoCAP at baseline, end of the double-blind phase, and end of OL phase.RESULTS: By the end of the OL phase, 15.9% of infants with AD developed at least 1 food allergy; allergy to peanut was most common (6.6%), followed by cow's milk (4.3%) and egg white (3.9%). Seafood, soybean, and wheat allergies were rare. Levels of sIgE for milk, egg, and peanut increased with severity of AD, as determined by Investigator's Global Assessment score. We assigned sIgE decision points for the 6 foods and tested their ability to predict definite food allergy in this population. Positive predictive values for published and newly developed sIgE decision points were low (,0.6 for all values tested). CONCLUSIONS:In a large cohort of infants at risk for development of food allergy, sIgE levels were not clinically useful for predicting food allergy development. WHAT'S KNOWN ON THIS SUBJECT:Food allergies are often thought to be a common trigger in atopic dermatitis (AD). Serum immunoglobulin E is frequently used to assess food sensitization and clinical allergy, but few studies have assessed it longitudinally in infants and children with AD. WHAT THIS STUDY ADDS:In a large infant population with mild to moderate AD, 15.9% of patients developed food allergy during the study. Serum immunoglobulin E decision points had low positive predictive values, indicating that they are of limited use in this population.

Food allergy: immune mechanisms, diagnosis and immunotherapy

“…When IgE-mediated food allergy is suspected, measurements of total and allergen-specific serum IgE (sIgE) levels and skin prick tests (SPTs) are recommended to identify the causative food, although they are not in themselves diagnostic 16 . Increased sIgE levels may suggest food allergy, and sIgE thresholds with a 95% positive predictive value have been determined for some food allergens; for example, in peanut-allergic patients, the threshold sIgE level for peanut antigen is 14 kU A /L (U A = allergen-specific units; 1 unit ≈ 2.4 ng IgE) 17,92,93 . SPTs provoke allergen-mediated mast cell degranulation in the skin, leading to wheal-and-flare reactions.…”

Young children with moderate‐to‐severe atopic dermatitis can be treated safely and effectively with either topical tacrolimus or mild corticosteroids

“…A disrupted skin barrier plays a major role in the pathogenesis predisposing to eczema and further to allergic rhinitis and asthma . Up to 16% of children with moderate‐to‐severe atopic dermatitis show sensitisation to food allergens in the first 2 years of life . They are at later risk of sensitisation to inhaled allergens, which, again, is a risk factor for respiratory diseases such as asthma and airway hyperresponsiveness …”

“…2 Up to 16% of children with moderate-to-severe atopic dermatitis show sensitisation to food allergens in the first 2 years of life. 3 They are at later risk of sensitisation to inhaled allergens, 4 which, again, is a risk factor for respiratory diseases such as asthma and airway hyperresponsiveness. 2 Infants with moderate-to-severe dermatitis are often undertreated due to concern about adverse effects from topical medications.…”

Atopic Dermatitis Progression: Evaluating Intervention Strategies

“…Although older studies estimated an AD/food allergy comorbidity incidence for mild to moderate AD of 30% to 40%, more recent evidence shows that the incidence actually is about 15% in this subpopulation of patients 15 ; the incidence of food allergy among patients with severe AD is approximately 35%. 16 Interestingly, a review and meta-analysis of prospective studies shows that breastfeeding may decrease the incidence of AD.…”