Food, drug, insect sting allergy, and anaphylaxis
Identifying infants at high risk of peanut allergy: The Learning Early About Peanut Allergy (LEAP) screening study

https://doi.org/10.1016/j.jaci.2012.09.015Get rights and content

Background

Peanut allergy (PA) is rare in countries in which peanuts are introduced early into infants’ diets. Learning Early About Peanut Allergy (LEAP) is an interventional study aiming to assess whether PA can be prevented by oral tolerance induction.

Objective

We sought to characterize a population screened for the risk of PA.

Methods

Subjects screened for the LEAP interventional trial comprise the LEAP screening study cohort. Infants were aged 4 to 10 months and passed a prescreening questionnaire.

Results

This analysis includes 834 infants (mean age, 7.8 months). They were split into the following: group I, patients with mild eczema and no egg allergy (n = 118); group II, patients with severe eczema, egg allergy, or both but 0-mm peanut skin prick test (SPT) wheal responses (n = 542); group III, patients with severe eczema, egg allergy, or both and 1- to 4-mm peanut wheal responses (n = 98); and group IV, patients with greater than 4-mm peanut wheal responses (n = 76). Unexpectedly, many (17%) in group II had peanut-specific IgE sensitization (≥0.35 kU/L); 56% of group III were similarly sensitized. In contrast, none of the patients in group I and 91% of those in group IV had peanut-specific IgE sensitization. Sensitization on skin testing to peanut (SPT response of 1-4 mm vs 0 mm) was associated with egg allergy and severe eczema (odds ratio [OR], 2.31 [95% CI, 1.39-3.86] and 2.47 [95% CI, 1.14-5.34], respectively). Similar associations were observed with specific IgE sensitization. Black race was associated with a significantly higher risk of peanut-specific IgE sensitization (OR, 5.30 [95% CI, 2.85-9.86]). Paradoxically, for a given specific IgE level, black race was protective against cutaneous sensitization (OR, 0.15 [95% CI, 0.04-0.61]).

Conclusion

Egg allergy, severe eczema, or both appear to be useful criteria for identifying high-risk infants with an intermediate level of peanut sensitization for entry into a PA prevention study. The relationship between specific IgE level and SPT sensitization needs to be considered within the context of race.

Section snippets

Study design

The LEAP screening study is a single-center, prospective, observational study that includes infants who underwent screening for an interventional trial termed the LEAP study (see the Methods section in this article's Online Repository at www.jacionline.org), which investigated the prevention of PA in high-risk children. Recruitment was targeted to families with young infants with eczema, egg allergy, or both. In this article the term eczema is identical to the term atopic dermatitis.

Demographics of screened subjects

Infants were recruited for the LEAP study from November 2006 to May 2009. A total of 2829 potential participants contacted the clinical trials unit, and 899 underwent screening (see Fig 1 for details). Of these, 65 were not considered further because the appropriate LEAP stratum was closed or they withdrew consent or for other reasons. The remaining 834 subjects comprise the LEAP screening study cohort. For these, mean age was 7.8 months (range, 4-10 months), with slightly more male subjects

Discussion

An intervention needs to be directed at a population that is at high risk of PA, without having already had allergy, to successfully prevent PA. The study definition of “high risk” included egg allergy, severe eczema, or both. Our analysis demonstrates that the LEAP study recruitment strategy was able to identify an appropriate atopic population of young infants because the majority of enrolled infants had detectable peanut-specific IgE levels at screening. Our data demonstrate that the

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    This study was supported by the Immune Tolerance Network (funded by the National Institute of Allergy and Infectious Diseases); the Food Allergy Initiative, New York, NY; the Food Standards Agency, United Kingdom; the Food Allergy and Anaphylaxis Network, Fairfax, Va; the MRC & Asthma UK Centre; and the Department of Health through the National Institute for Health Research (NIHR) comprehensive Biomedical Research Centre award to Guy's & St Thomas' NHS Foundation Trust in partnership with King's College London and King's College Hospital NHS Foundation Trust. The clinical trials unit is supported by the National Peanut Board, Atlanta, Ga.

    Disclosure of potential conflict of interest: G. Roberts has received research support from the Immune Tolerance Network (ITN). P. H. Sayre has received travel support from the National Institute of Allergy and Infectious Diseases (NIAID). H. T. Bahnson and H. Mitchell have received research support from the National Institutes of Health. S. Radulovic has received research support from the ITN/NIAID, the Food Allergy Initiative, and the National Peanut Board and has received travel support from Stallergenes and the Allergy Academy. S. Chan has received research support from the ITN/NIAID, the Food Allergy Initiative, the National Peanut Board, the Food Standards Agency, the Food Allergy & Anaphylaxis Network, MRC & Asthma UK Centre, and the Department of Health through the National Institute for Health Research Comprehensive Biomedical Research Centre award to the Guy's and St Thomas' NHS Foundation Trust in partnership with King's College London and King's College Hospital NHS Foundation Trust. V. Turcanu has received research support from the ITN. G. Lack has received research support from the ITN/NIAID, the Food Allergy Initiative, the National Peanut Board, the Food Standards Agency, the Food Allergy and Anaphylaxis Network, MRC Asthma UK Centre, and the Department of Health through the National Institute for Health Research Comprehensive Biomedical Research Centre award to the Guy's & St Thomas' NHS Foundation Trust in partnership with King's College London and King's College Hospital NHS Foundation Trust; is on the DBV Technologies advisory board; is a voluntary scientific advisor for the Anaphylaxis Campaign and the National Peanut Board; has received lecture fees from Sodilac, Novartis, Nestlé Nutrition, GlaxoSmithKline, and the Serono Symposia International Foundation; and has stock/stock options in DBV Technologies. The rest of the authors declare that they have no relevant conflicts of interest.

    These authors contributed equally to this work.

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