The natural history and clinical predictors of egg allergy in the first 2 years of life: a prospective, population-based cohort study.

BACKGROUND: There is a paucity of data examining the natural history of and risk factors for egg allergy persistence, the most common IgE-mediated food allergy in infants. OBJECTIVE: We aimed to assess the natural history of egg allergy and identify clinical predictors for persistent egg allergy in a population-based cohort. METHODS: The HealthNuts study is a prospective, population-based cohort study of 5276 infants who underwent skin prick tests to 4 allergens, including egg. Infants with a detectable wheal were offered hospital-based oral food challenges (OFCs) to egg, irrespective of skin prick test wheal sizes. Infants with challenge-confirmed raw egg allergy were offered baked egg OFCs at age 1 year and follow-up at age 2 years, with repeat OFCs to raw egg. RESULTS: One hundred forty infants with challenge-confirmed egg allergy at age 1 year participated in the follow-up. Egg allergy resolved in 66 (47%) infants (95% CI, 37% to 56%) by 2 years of age; however, resolution was lower in children with baked egg allergy at age 1 year compared with baked egg tolerance (13% and 56%, respectively; adjusted odds ratio, 5.27; 95% CI, 1.36-20.50; P = .02). In the subgroup of infants who were tolerant to baked egg at age 1 year, frequent ingestion of baked egg (≥5 times per month) compared with infrequent ingestion (0-4 times per month) increased the likelihood of tolerance (adjusted odds ratio, 3.52; 95% CI, 1.38-8.98; P = .009). Mutation in the filaggrin gene was not associated with the resolution of either egg allergy or egg sensitization at age 2 years. CONCLUSION: Phenotyping of egg allergy (baked egg tolerant vs allergic) should be considered in the management of this allergy because it has prognostic implications and eases dietary restrictions. Randomized controlled trials for egg oral immunotherapy should consider stratifying at baseline by the baked egg subphenotype to account for the differential rate of tolerance development.

Vitamin D insufficiency is associated with challenge-proven food allergy in infants.

BACKGROUND: Epidemiological evidence has shown that pediatric food allergy is more prevalent in regions further from the equator, suggesting that vitamin D insufficiency may play a role in this disease. OBJECTIVE: To investigate the role of vitamin D status in infantile food allergy. METHODS: A population sample of 5276 one-year-old infants underwent skin prick testing to peanut, egg, sesame, and cow's milk or shrimp. All those with a detectable wheal and a random sample of participants with negative skin prick test results attended a hospital-based food challenge clinic. Blood samples were available for 577 infants (344 with challenge-proven food allergy, 74 sensitized but tolerant to food challenge, 159 negative on skin prick test and food challenge). Serum 25-hydroxyvitamin D levels were measured by using liquid chromatography tandem mass spectrometry. Associations between serum 25-hydroxyvitamin D and food allergy were examined by using multiple logistic regression, adjusting for potential risk and confounding factors. RESULTS: Infants of Australian-born parents, but not of parents born overseas, with vitamin D insufficiency (≤50 nmol/L) were more likely to be peanut (adjusted odds ratio [aOR], 11.51; 95% CI, 2.01-65.79; P=.006) and/or egg (aOR, 3.79; 95% CI, 1.19-12.08; P=.025) allergic than were those with adequate vitamin D levels independent of eczema status. Among those with Australian-born parents, infants with vitamin D insufficiency were more likely to have multiple food allergies (≥2) rather than a single food allergy (aOR, 10.48; 95% CI, 1.60-68.61 vs aOR, 1.82; 95% CI, 0.38-8.77, respectively). CONCLUSIONS: These results provide the first direct evidence that vitamin D sufficiency may be an important protective factor for food allergy in the first year of life.

Can early introduction of egg prevent egg allergy in infants? A population-based study.

BACKGROUND: Infant feeding guidelines have long recommended delaying introduction of solids and allergenic foods to prevent allergy in high-risk infants, despite a paucity of evidence. OBJECTIVE: We aimed to determine whether confirmed egg allergy in 12-month-old infants is associated with (1) duration of breast-feeding and (2) ages of introducing egg and solids. METHODS: In a population-based cross-sectional study (HealthNuts) parents reported on infant feeding and potential confounding factors before skin prick testing for egg white. Egg-sensitized infants were then offered an egg oral food challenge. Multiple logistic regression was used to investigate associations between diet and egg allergy adjusted for possible confounding factors. RESULTS: A total of 2589 infants (73% response) participated. Compared with introduction at 4 to 6 months, introducing egg into the diet later was associated with higher risks of egg allergy (adjusted odds ratios [ORs], 1.6 [95% CI, 1.0-2.6] and 3.4 [95% CI, 1.8-6.5] for introduction at 10-12 and after 12 months, respectively). These findings persisted even in children without risk factors (OR, 3.3 [95% CI, 1.1-9.9]; 10-12 months). At age 4 to 6 months, first exposure as cooked egg reduced the risk of egg allergy compared with first exposure as egg in baked goods (OR, 0.2 [95% CI, 0.06-0.71]). Duration of breast-feeding and age at introduction of solids were not associated with egg allergy. CONCLUSIONS: Introduction of cooked egg at 4 to 6 months of age might protect against egg allergy. Changes in infant feeding guidelines could have a significant effect on childhood egg allergy and possibly food allergy more generally.

IgE food sensitization in infants with eczema attending a dermatology department.

OBJECTIVES: Because community-based studies, which report IgE food sensitization (IgE-FS) in more than 80% of infants with moderate atopic eczema, may be influenced by referral bias, we assessed the prevalence of IgE-FS in a cohort of infants with moderate atopic eczema attending a dermatology department clinic. STUDY DESIGN: Consecutive infants (n = 51, 39 males; median age, 34 weeks; range, 20 to 51 weeks) with moderate atopic eczema referred to a university-affiliated dermatology department were studied prospectively. Clinical history and eczema severity were documented. IgE-FS was assessed by the skin prick test (SPT; n = 51) and food-specific serum IgE antibodies (CAP-FEIA test; n = 41). IgE-FS was diagnosed if the SPT or CAP-FEIA level exceeded the >95% predictive reference cutoff for positive food challenges. RESULTS: Based on SPT, 44 of 51 infants (86%; 95% confidence interval [CI] = 74% to 94%) had IgE-FS (cow's milk, 16%; egg, 73%; peanut, 51%). Using age-specific 95%-predictive cutoff values, CAP-FEIA identified 34 of 41 infants (83%; 95% CI = 68% to 93%) with IgE-FS (cow's milk, 23%; egg, 80%). Forty-six (90%) infants had IgE-FS to at least 1 food item by either SPT or CAP-FEIA. CONCLUSIONS: Atopic eczema was found to be closely associated with IgE-FS in infants attending a dermatology department.