Identifying infants at high risk of peanut allergy: The Learning Early About Peanut Allergy (LEAP) screening study

George Du Toit, MBBCh, FRCPCH
- King's College London, King's Health Partners, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, and the Department of Paediatric Allergy, Guy's and St Thomas' NHS Foundation Trust, London;
- These authors contributed equally to this work.
Graham Roberts, MD
- University of Southampton, Southampton, United Kingdom
- These authors contributed equally to this work.
Peter H. Sayre, MD, PhD
- Immune Tolerance Network and University of California, San Francisco, Calif
Marshall Plaut, MD
- National Institute of Allergy and Infectious Diseases, Bethesda, Md
Henry T. Bahnson, MPH
- Rho Federal Systems, Chapel Hill, NC
Herman Mitchell, PhD
- Rho Federal Systems, Chapel Hill, NC
Suzana Radulovic, MD
- King's College London, King's Health Partners, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, and the Department of Paediatric Allergy, Guy's and St Thomas' NHS Foundation Trust, London;
Susan Chan, MD
- King's College London, King's Health Partners, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, and the Department of Paediatric Allergy, Guy's and St Thomas' NHS Foundation Trust, London;
Adam Fox, MD
- King's College London, King's Health Partners, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, and the Department of Paediatric Allergy, Guy's and St Thomas' NHS Foundation Trust, London;
Victor Turcanu, MD
- King's College London, King's Health Partners, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, and the Department of Paediatric Allergy, Guy's and St Thomas' NHS Foundation Trust, London;
Gideon Lack, MD, FRCPCH
- King's College London, King's Health Partners, MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, and the Department of Paediatric Allergy, Guy's and St Thomas' NHS Foundation Trust, London;
- Corresponding author: Gideon Lack, MD, FRCPH, Paediatric Allergy Research, 2nd Floor, South Wing, St Thomas' Hospital, London SE1 7EH, United Kingdom.
Learning Early About Peanut Allergy (LEAP) Study Team

Received 28 June 2012; received in revised form 4 September 2012; accepted 10 September 2012. published online 21 November 2012.
Corrected Proof

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.

Key words: Peanut sensitization, peanut allergy, allergy risk factors, eczema, egg allergy, patient recruitment, allergy prevention, LEAP study