The natural history of tree nut allergy

Background: Although 20% of children outgrow peanut allergy, the natural history of tree nut (TN) allergy has not been well studied. Objective: The goals of the study were to estimate the proportion of children who outgrow TN allergy and examine predictors of outgrowing it. Methods: Patients with TN allergy, defined as a history of reaction on ingestion and evidence of TN-specific IgE (TN-IgE) or positive TN-specific IgE level but no history of ingestion, were evaluated. If all current TN-IgE levels were less than 10 kilounits of antibody (kU_A)/L, double-blind, placebo-controlled food challenges were offered. Patients who had undergone open TN challenges as part of routine clinical care were also included. Results: Two hundred seventy-eight patients with TN allergy were identified. One hundred one (36%) had a history of acute reactions, 12 (12%) of whom had reactions to multiple TNs and 73 (63%) of whom had a history of moderate-to-severe reactions. Nine of 20 patients who had previously reacted to a TN passed challenges, so that 9 (8.9%; 95% CI, 4% to 16%) of 101 patients with a history of prior TN reactions outgrew TN allergy. Fourteen of 19 who had never ingested TNs but had detectable TN-specific IgE levels passed challenges. One hundred sixty-one did not meet the challenge criteria, and 78 met the criteria but declined challenges. Looking at specific TN-IgE cutoffs, 58% with TN-IgE levels of 5 kU_A/L or less and 63% with TN-IgE levels of 2 kU_A/L or less passed challenges. Conclusions: Approximately 9% of patients outgrow TN allergy, including some who had prior severe reactions. Although ideal cutoffs for challenge cannot be firmly recommended on the basis of these data, patients aged 4 years or older with all TN-IgE levels of 5 kU_A/L or less should be considered for challenge.