Atopic dermatitis common among children with food allergies but rarely triggered by food

Although food allergy appeared common among children with atopic dermatitis, only 3% had food-triggered atopic dermatitis, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.

Because of the risks of unnecessarily eliminating foods, including nutritional deficiencies and loss of tolerance, detailed food allergy histories should be obtained from patients with atopic dermatitis, including testing and oral food challenges if indicated, Jennifer Chen Li, MD, an allergy/immunology fellow with the Massachusetts General Hospital division of rheumatology, allergy and immunology, and colleagues wrote.

To distinguish the prevalence of food-triggered AD from IgE-mediated food allergy, the researchers conducted a retrospective chart review of 372 children with AD who were referred to allergy and/or dermatology specialists at a tertiary care referral center with one or more follow-up visits.

The children (63% boys; 76% white; 92% non-Hispanic) had a median age at first specialist visit of 1.1 years (range, 0 to 16 years), with 29% diagnosed with moderate AD and 18% diagnosed with severe AD.

Most patients with AD (55%) had IgE-mediated food allergy, including 60% of those with mild AD, 45% of those with moderate AD and 57% of those with severe cases of AD. About two-thirds (67%) of patients with food allergy were boys, and a greater proportion of patients with vs. without IgE-mediated food allergy were aged younger than 1 year at the initial visit (48% vs. 26%; P < .001).

The most common allergens associated with immediate-type food allergy included peanut (44%) and egg (43%). Also, 65% of patients with IgE-mediated food allergy had skin prick test or IgE levels with positive predictive values greater than 95%.

Food-triggered AD (FTAD) — defined by a physician-noted sustained improvement in AD after removal of a food — appeared uncommon, occurring in only 3% of the total cohort and 2% of patients with mild AD, 6% of those with moderate AD and 4% with severe AD.

Additionally, 4% of patients with an IgE-mediated food allergy to at least one food had FTAD for another food.

The most common allergens for FTAD were egg (62%) and peanut (31%). OFC was used to confirm the diagnosis of approximately 30% of patients with FTAD.

Among the 97 patients who only were referred for AD and not food allergy, 29% had IgE-mediated food allergy, 13% had mild AD, 28% had moderate AD and 41% had severe AD, while 5% developed FTAD.

A very small number of patients may experience better AD outcomes with food elimination diets, the researchers continued, but risks include nutritional deficiencies and loss of tolerance.

Providers should then carefully consider prescribing food elimination diets for AD when there are no immediate food allergy symptoms, with clinical decision-making focused on symptoms of IgE-mediated food allergy in most cases.

Even among patients who only were referred for AD, the researchers concluded, food allergy was common, although FTAD was rare. Noting that their study was retrospective, the researchers also said that prospective studies are necessary to further characterize the connection between food allergy and AD.