Families with a child who has food allergy often wonder if a younger sibling should be screened before introducing potentially allergenic foods. According to a study published in the Journal of Allergy and Clinical Immunology: In Practice, this approach may be unwarranted given the high rate of false-positive test results and low risk of food allergy in siblings.
"Our data suggests that the risk of food allergy in siblings of an affected child is only minimally higher than in the general population," says lead author Ruchi Gupta, MD, MPH, pediatrician and researcher at Ann & Robert H. Lurie Children's Hospital of Chicago and Associate Professor of Pediatrics and Medicine at Northwestern University Feinberg School of Medicine. "We also observed that testing might show sensitization to peanuts in a child who has never had peanuts, for example, but that might not mean that eating a peanut will provoke allergic symptoms in that child."
The study found that the majority (53%) of siblings of food allergic children showed food sensitization with testing, but did not experience food allergy symptoms. An additional one-third of siblings tested negative and had no allergic reactions to food, while only 13.6% of siblings had a true food allergy.
"Our findings help support the National Institute of Allergy and Infectious Diseases practice guidelines to not screen siblings before the child's initial exposure to a food," says Gupta. "Routine screening without a history of allergic food reactions might lead to unnecessary food avoidance in kids who can actually tolerate that food, which impacts quality of life and nutrition. Food avoidance also increases the risk of developing an allergy to that food."
A total of 1,120 children participated in the study, including food allergic kids and their biological siblings. Food allergy status was determined by applying a set of stringent clinical criteria to data gathered from a questionnaire-based interview, as well as results of specific IgE blood test and skin prick testing.
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