Food allergy, dermatologic diseases, and anaphylaxis
The natural history of tree nut allergy

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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 (kUA)/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 kUA/L or less and 63% with TN-IgE levels of 2 kUA/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 kUA/L or less should be considered for challenge.

Section snippets

Study population

Clinic records of patients from The Johns Hopkins Pediatric Allergy Clinic who had been given a diagnosis of TN allergy were reviewed to collect demographic and clinical data. A diagnosis of TN allergy was defined as either a clear-cut clinical history of an allergic reaction on ingestion and a confirmatory positive test response for TN-IgE or a history of a positive TN skin prick test (SPT) response or positive TN-IgE level (>0.35 kilounits of antibody [kUA]/L) without history of ingestion.

Study population

A total of 278 patients, with an age range of 3 to 21.6 years (median, 6.9 years) at the time of evaluation, were enrolled in the study and are described in Table I. There were 180 male (65%) and 98 female (35%) patients, and their TN allergies had been diagnosed between the ages of 3 months and 15.8 years (median, 1.3 years). The initial diagnosis was made on the basis of a history of an acute reaction to a TN or multiple TNs in 101 patients, 13 of whom had positive SPT responses and 88 of

Discussion

These findings confirm that a subset of children with TN allergy outgrow their allergy over time, although the resolution rate appears to be less than in peanut allergy. The data suggest that children with TN allergy should be re-evaluated periodically to assess whether they have acquired oral tolerance. In addition, TN-IgE levels can be used to estimate the likelihood that a patient has outgrown his or her TN allergy and guide selection of appropriate candidates for TN challenges.

Our estimate

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Supported by National Institutes of Health training grant T32 AI 07007 from the National Institute of Allergy and Infectious Disease, the Eudowood Foundation for the Consumptives of Maryland, The Myra Reinhard Family Foundation, and General Clinical Research Center grant M01-RR000052.

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