According to new research, peanut tolerance in siblings could be predicted by a negative test result prior to introduction.
A Canadian study published in the June 2016 found that siblings whose peanut allergy tests were negative prior to introduction did not have an allergic response when they ate peanut for the first time. The study included 154 younger siblings of peanut allergic children. The participants had never eaten peanut and ranged in age from under 12 months to over 5 years, with a median age of 23 months.
Performed Tests Double-blinded skin prick tests were performed with peanut extract and peanut butter and blood samples were collected for peanut-specific IgE analysis then parents fed peanut products to all the children under medical supervision.
Results Eight siblings experienced allergic reactions in response to peanut introduction. Of these, five needed to be given epinephrine and one child required two epinephrine injections and was later hospitalized. All of the eight reactive children had either skin test reactivity to peanut or high concentrations of peanut-specific IgE antibodies prior to eating peanut.
Summary There is an increased risk of anaphylaxis upon peanut introduction in siblings of children with peanut allergy. Most parents are reluctant to give peanuts to the younger sibling at home without testing. The good news is that allergy testing prior to introduction was negative in over 90% of cases which according to the researchers it carries a high negative predictive value.