HOUSTON – Food-allergic children undergoing a double-blind, placebo-controlled food challenge test can safely be discharged home after 2 hours provided they haven’t experienced a severe immediate reaction in the interim, according to a large retrospective Dutch study.
Late reactions are unpredictable and very seldom severe, Jacquelien Saleh-Langenberg reported at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
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No severe late reactions occurred in children who underwent placebo-controlled food challenges with cow’s milk, cashew, peanut, egg, and hazelnut.
She presented a study of 1,142 children who underwent double-blind, placebo-controlled food challenge testing at a tertiary clinic at the University of Groningen in the Netherlands, where she is a combined medical student and Ph.D. candidate. The food-allergic children were challenged with cow’s milk, peanut, cashew, hazelnut, and egg.
A total of 400 children developed late reactions: 20.8% of children reported late reactions only on an active challenge day, 9.6% only on a placebo challenge day, and 4.6% reported reactions on both active and placebo challenge days.
Of particular interest was the finding that 89 subjects developed isolated reactions on an active challenge day and 92 did so on a placebo challenge day.
“Isolated late reactions occurred with comparable frequency after active and placebo challenge and are thus unlikely to be a real phenomenon,” Ms. Saleh-Langenberg concluded.
Late reactions were manifest as gastrointestinal symptoms in 45% of cases and cutaneous symptoms in about one-third, with respiratory symptoms accounting for most of the remainder. Ninety-eight percent of late reactions were rated as mild to moderate, having a score of 1-6 on a 12-point severity scale.
The investigators developed a predictive model for late reactions occurring on an active challenge day. It proved to have little practical value, though. The model, which included age, allergic rhinitis, severity of any immediate reaction, and hazelnut allergy, explained a mere 8% of the variance in the incidence of late reactions.
When late reactions occurred on an active challenge day, they did so a mean of 3.5 hours after testing. When they occurred on a placebo challenge day, they happened a mean of 4 hours after the challenge. The reactions took an average of 2 hours and 1 hour, respectively, to disappear.
Ms. Saleh-Langenberg reported no conflicts of interest with regard to this university-supported study.