The Natural History of Tree Nut Allergy

Purpose of the Study. To estimate the proportion of children who outgrow tree nut (TN) allergy and examine predictors of outgrowing it. Study Population. All children with TN allergy followed at the authors’ pediatric allergy clinic. Methods. Patients with TN allergy, defined as a history of reaction on ingestion and evidence of TN-specific immunoglobulin E (TN-IgE) or positive TN-specific IgE level but no history of ingestion, were evaluated. If all current TN-IgE levels were <10 kU of antibody (kUA)/L, double-blind, placebo-controlled food challenges were offered. Patients who had undergone open oral 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% confidence interval: 4%–16%) of 101 patients with a history of previous TN reactions outgrew TN allergy. Of 19 patients who had never ingested TNs but had detectable TN-specific IgE levels, 14 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 values, 58% with TN-IgE levels of ≤5 kUA/L and 63% with TN-IgE levels of ≤2 kUA/L passed challenges. Conclusions. Approximately 9% of patients outgrow TN allergy, including some who had previous 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 kUA/L should be considered for physician-supervised oral food challenges. Reviewer Comments. This is the first study to comprehensively address the natural history of TN allergy. Although the 9% chance of outgrowing TN allergy may seem low, it may be an underestimate of the actual resolution rate, because a large number of eligible patients declined diagnostic food challenges. The results of this study should encourage regular follow-up of children with TN allergy and consideration, when clinically indicated, for physician-supervised oral food challenges to determine the possibility of resolution. Because these oral food challenges can trigger anaphylaxis, they are generally undertaken under the supervision of an allergist and with immediate access to medications and equipment to treat a significant allergic reaction.