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Thursday, March 23, 2017

Novel baseline predictors of adverse events during oral immunotherapy in children with peanut allergy

Food allergy is a huge problem affecting 3 to 8% of school-age children.  So far, avoidance and supportive management have been the mainstays of therapy, but this is rapidly changing with studies showing the efficacy of oral immunotherapy (OIT), especially for peanut allergies.  In peanut OIT, gradually increasing doses of peanut are given as part of the buildup, with steady doses given during maintenance.  The hope is to desensitize the immune system so that reactions are not as severe.  In this month’s issue of JACI, Virkud and colleagues discuss the safety of oral immunotherapy to peanut by examining 104 patients from 3 peanut OIT trials (J Allergy Clin Immunol 2017; 139(3): 882-888).  They look at the past medical history, parental reports, daily symptom diaries, and relationship to dose escalations to determine the risks and predictors of adverse effects (AEs). 

The rate of AEs was high, with 80% experiencing at least 1 episode, and over 90% of these occurring at home.  42% of AEs were systemic reactions, but fewer than 50% received epinephrine, indicating a need for better patient education.  About half of these AEs were gastrointestinal, and half of the patients who dropped out did so due to these gastrointestinal AEs; this amounted to 10% of all enrolled patients.

Overall, allergic rhinitis and the wheal size on peanut skin prick testing (SPT) were significant predictors of AEs.  Allergic rhinitis approximately doubled the likelihood of having an AE, and seemed to explain why there was a higher rate of AEs during the spring and the fall.  Asthma was also predictive of AEs during maintenance, but not in the buildup phase.  Gastrointestinal AEs, like abdominal pain, nausea, vomiting, difficulty swallowing, and diarrhea, were also associated with the peanut SPT wheal size. 

While there remains a lot to be learned about oral immunotherapy, this study helps to determine who would be the best candidates for this promising means of treating food allergies.  Virkud and colleagues conclude that until there are rigorous well-designed and controlled trials, avoidance should remain the current standard of care.

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