New Research on Food Allergies and Atopic Dermatitis
Children with atopic dermatitis (often called eczema), have a higher risk for developing food allergies. Two recently published studies provide new insights into the relationship between food allergies and eczema.
One study, published online last month in the Journal of Allergy and Clinical Immunology: In Practice, examined the risk of developing immediate reactions in children avoiding food because of food-triggered eczema, while the other, published in the December issue of Pediatrics, discusses the limitations of allergy-specific blood test results in infants with eczema in predicting the development of food allergy.
Food allergies are more likely to cause eczema in those under the age of 5, while aeroallergens are more likely to cause eczema in older children and adults. A study recently published by the Journal of Allergy and Clinical Immunology: In Practice looked at food-triggered eczema. Exposure to a food allergen via ingestion can cause both IgE-mediated (or immediate) reactions and non-IgE-mediated (or delayed type) reactions, such as an exacerbation of eczema that typically occurs 6 to 48 hours after ingestion. Once a patient is diagnosed with food-triggered eczema, he or she is typically instructed to begin an elimination diet.
No large-scale study has been conducted to determine the incidence of the development of immediate reactions in children who previously had only delayed type reactions. Researchers at the Ann and Robert H. Lurie Children’s Hospital of Chicago sought to find out how often immediate reactions occur and identify the characteristics of these patients.
Using pediatric patient records from 2003-2010 at the Lurie Children’s allergy-immunology clinic, researchers collected data from nearly 300 patient charts, all of which were enrolled because there was concern for food-triggered eczema. Researchers collected data from subsequent clinic visits that included eczema severity, development of reactions to food, food-specific IgE levels, foods that were being avoided and results of oral food challenges to determine immediate or delayed type reactions. Immediate reactions were defined by timely development of typical symptoms such as hives, vomiting and anaphylaxis after food ingestion.
Patients were on a food elimination diet if there were foods thought to be causing eczema or if there was a clear history of immediate reaction following ingestion of a food. The most common foods attributed to eczema flares were milk, egg and soy.
During follow-up, 132 patients were diagnosed with food-triggered eczema. Among 54 patients from the total initial cohort, there were 60 immediate reactions upon accidental ingestion or oral food challenge in the clinic during the follow-up period. Alarmingly, the authors wrote, 25 of those patients had no previous history of immediate reactions at their initial visit but developed a total of 31 immediate reactions during follow-up.
“As the development of immediate reactions was more common than suspected, we next sought to describe risk factors for the development of immediate reactions,” the authors wrote. “There was no difference in race, sex, age, family history, or other atopic disease status, although a personal history of asthma trended toward increased risk of immediate reactions at follow-up… Avoidance of food was associated with development of an immediate reaction.”
Researchers indicated they were surprised to learn that nearly 20 percent of patients with likely food-triggered eczema and no prior immediate reactions developed immediate reactions during the time they were followed for their eczema. New immediate reactions were as severe as anaphylaxis in nearly one-third of patients.
“Our study suggests that complete avoidance may not be the best management strategy in high-risk children even with food-triggered atopic dermatitis… exclusion diets need to be thoughtfully prescribed as they can inadvertently lead to loss of tolerance of foods and increase the risk of immediate reactions,” the authors wrote.
These findings are consistent with the recent Learning Early About Peanut Allergy Study, which found that early introduction and regular consumption of peanuts decreased the development of peanut allergy among atopic children. Researchers added that it does not appear that any one food is more likely to result in an immediate reaction compared with food-triggered eczema. Limitations of the study include lack of a case control group of patients with eczema without dietary restrictions and the fact that practices have evolved in recent years concerning the advice of food avoidance.
Future studies are warranted to investigate why some patients who previously only experienced delayed type reactions changed to immediate IgE-mediated reactions. In their conclusions, researchers also wrote that their data suggest that patients with food-triggered eczema warrant an emergency action plan and prescription for an epinephrine auto-injector.
Previous studies have documented a rate of food allergy in eczema patients ranging from 15 to 40 percent, with 30 to 40 percent as the most commonly cited range. It is well established that an oral food challenge is the gold standard for food allergy diagnosis, and that blood tests or skin tests alone should not be relied upon to diagnose a food allergy. But because food challenges are time-consuming and carry risks of serious reactions, it could be advantageous to determine whether there is a predictive value of allergen-specific IgE tests in patients with eczema.
In the Pediatrics study, researchers led by Jonathan Spergel, M.D., from the Children’s Hospital of Philadelphia, examined the predictive value of food-antigen-specific IgE measurements among infants with mild to moderate eczema with no prior history of other atopic conditions using data from patients ages 3 to 18 months enrolled in the Study of the Atopic March, a dual phased study that is designed to explore the long-term safety and efficacy of Elidel® in infants with eczema.
Researchers followed more than 1,000 patients enrolled in a 36-month randomized double-blind phase followed by an open-label phase up to 33 months. At the end, they learned:
- 16 percent of patients had developed a food allergy. The most common food allergens were peanut (6.6 percent), milk (4.3 percent) and egg white (3.9 percent).
- The magnitude of food allergy development was similar to that of other atopic conditions that occurred during the study – 10.7 percent developed asthma, 14.1 percent developed allergic conjunctivitis and 22.4 percent developed allergic rhinitis.
The study’s results indicated that screening allergen-specific IgE was not useful. Researchers found that the percentage of food allergies increased with the severity of a patient’s eczema (8 percent for those with mild eczema to 24 percent for those with severe eczema). “This finding adds to the body of work that supports the ‘atopic march,’ the hypothesis that [atopic dermatitis] pathology predisposes individuals to the development of other atopic diseases and comorbid conditions associated with impaired overall health and increased healthcare utilization,” the authors wrote.
“The article proves a point that allergists and dermatologists have thought for a long time -- random screening of infants with atopic dermatitis will lead to unnecessary food avoidance,” said study author Jonathan Spergel, M.D. “Screening specific IgE are not helpful in atopic dermatitis in infants. It is always important to get a history first.”
For more food allergy research, visit FARE’s website.