Timing of eczema onset influences food allergy development risk in childhood
The risk of developing food allergy at the age of 3 years is high among infants whose eczema occurred within the first 4 months of life, according to the results of T-CHILD* study.
“Our findings may contribute to a better understanding of the timing of eczema onset as a potentially modifiable risk factor and to defining those who may need to be on guard for food allergy,” a team of researchers from the National Center for Child Health and Development in Tokyo, Japan said.
The study population comprised 1,550 children born to 1,504 mothers. Of the 1,330 children included in the final analysis, 27.9 percent developed eczema in the first year of life. Eczema development was associated with parental history of allergic diseases (p<0.01), pet ownership (p=0.03), and annual household income (p<0.01). [J Dermatol Sci 2016;84:144–148]
Food allergy symptoms occurred at some point within the response period in 7.5 percent of 1,311 children with follow-up data at 1 year of age and in 7.5 percent of 1,136 of those with follow-up data at 3 years of age. Eggs and cow’s milk were the most common cause of food allergy (57.6 and 18.6 percent, respectively, at 1 year; 50.6 and 15.3 percent at 3 years).
Eczema during the first year of life was associated with a nearly 4-fold risk of developing food allergy at 3 years (adjusted odds ratio [aOR], 3.90; 95 percent CI, 2.34 to 6.52; p<0.001). There was no such relationship found between food allergy and any environmental or socioeconomic factors.
Particularly, the risk of food allergy at 3 years of age was highest among infants whose eczema occurred within the first 1 to 2 months (aOR, 6.61; 3.27 to 13.34; p<0.001) and 3 to 4 months (aOR, 4.69; 2.17 to 10.13; p<0.001) after birth.
“There was no significant association between food allergy at 12 months and eczema at 3 years of age (p=0.639), suggesting that there is no reverse causation,” researchers said.
The role of eczematous skin in the pathogenesis of food allergy has been reported previously. There is a strong suggestion that “exposure of eczematous skin, but not intact skin, to food proteins is a true risk factor for sensitization to food antigens,” they noted.
In an earlier report, the researchers described a significant reduction in the risk of atopic dermatitis/eczema, but not food sensitization, following daily application of a moisturizer to neonates with a family history of allergic disorders during the first 32 weeks of life. They pointed out the moisturizer served to protect skin barrier function, but not to prevent T-helper cell 2 immune responses.
“Thus, careful treatment of eczema is necessary for preventing food allergy, especially in infants with early-onset eczema,” they said. Another way to potentially decrease the incidence of food allergy is through “early introduction of solid food—even potentially allergy-inducing foods such as peanuts and eggs—to infants with well-controlled skin."
“Further research is warranted to clarify whether these strategies for infants with early-onset eczema can actually decrease development of food allergy,” they added.
The study may be limited by the use of parent-reported information regarding eczema and food allergy as the outcome. Furthermore, allergen sensitization was not confirmed by serum IgE measurement or skin prick test.*Tokyo Children’s Health, Illness and Development