Introduction
Food allergies pose a significant public health concern due to their
increasing incidence in infants and children in the last few decades
worldwide, and particularly in industrialized
countries.1,2 Emerging treatments, including oral and
epicutaneous immunotherapy for food allergies, are still considered
investigational because of safety concerns and uncertain long-term
efficacy.3 Thus, the conventional management for
patients with food allergies remains strict avoidance of the allergenic
food and being prepared for any adverse reactions from unintended food
ingestion.4 Since many children with a food allergy
outgrow the disease,5 a practical strategy is to wait
for “the day of resolution” by observing the current management
principle.
Recently, however, observations that dietary inclusion of baked hen’s
egg or cow’s milk accelerated resolution of egg or milk allergy have
attracted attention.6-11 Although evidence for the
potential of baked products to promote outgrowing the disease still
awaits well–designed randomized controlled studies,12partial liberalization of a child’s diet may be beneficial due to the
improved quality of life and nutritional status.13
To ascertain the safety of implementing such diet liberalization, it is
necessary to first perform oral food challenge (OFC) to determine the
quantity of food that a patient can consume without triggering an
allergic reaction. In the baked egg/milk diet, a patient must pass an
OFC with baked egg containing 1 whole
egg6,7 or baked
milk containing 0.5–1.3 g of milk protein (equivalent to 15–40 mL of
milk).8-11 The
allergenicity of the baked products is assumed to be reduced, but
children who nevertheless react to that quantity of allergen should
completely avoid the food. However, they may safely consume a lesser
amount of the allergen—such as 10 g of butter (equivalent to 2.9 mL of
milk)—than that in the recommended baked diet.14 In
Japan, the national health insurance covers OFC testing, and
guidelines15 provide dietary guidance on how to
consume a small, safe amount of an allergenic food based on the results
of readily available OFC using a low dose of allergen. Dietary
liberalization is now increasingly recommended and performed in
pediatric practice in Japan.
This new approach to management of food allergy seems to be beneficial
to the patients. The natural course of food allergy, however, varies
widely from tolerance to persistence,5 which may
affect results of the management. Reported predictors of persistence of
a food allergy in the natural course include a history of anaphylaxis,
the presence of another food allergy, comorbid allergic diseases such as
asthma, reaction to even a low dose, elevated allergen–specific IgE
(sIgE) levels, etc.5,16,17 In addition, it was
reported that mothers with a high level of anxiety, even after a
negative OFC for their child, were reluctant to reintroduce the
offending food.18 Psychological factors may affect the
natural history of food allergy.
We therefore designed and conducted the IQ–OFA (Impact of QoL on
Outgrowing Food Allergy) study to identify factors that are associated
with natural outgrowing of food allergies in children, with special
focus on the QoL. In the current study, we aimed to investigate factors
related to successful reintroduction of egg to the diet of egg–allergic
children after OFC–based dietary advice. Our findings may contribute to
children’s ability to naturally outgrow food allergies.