LEAPing through the looking glass: secondary analysis of the effect of skin test size and age of introduction on peanut tolerance after early peanut introduction

Abstract

Background: In the Learning Early About Peanut Allergy (LEAP) study, early peanut introduction in high-risk 4- to 11-month-olds was associated with a significantly decreased risk of developing peanut allergy. However, the influences of key baseline high-risk factors on peanut tolerance are poorly understood.

Methods: Secondary analysis was conducted on the publically available LEAP dataset, exploring relationships between peanut tolerance, baseline peanut/egg sensitization, eczema severity/duration, age of introduction, gender, and race.

Results: A multiple logistic regression model predicting odds of successful oral food challenge (OFC) at 60 months noted higher odds with early introduction (OR 9.2, P < 0.001, 95% CI 4.2-20.3), white race (OR 2.1, P = 0.04, 95% CI 1.1-3.9), and advancing age (OR 4.8, P = 0.04, 95% CI 1.1-20.8). Odds of peanut tolerance were lower with increasing peanut wheal size (OR 0.58, P < 0.001, 95% CI 0.46-0.74), increased baseline SCORAD score (OR 0.98, P = 0.04, 95% CI 0.97-1), and increased kU_A /l of egg serum IgE (sIgE) (OR 0.99, P = 0.04, 95% CI 0.98-1). The probability of peanut tolerance in the early introduction group was 83% vs 43% in the avoidance group with SPT wheal of <4 mm. The probability of a successful OFC was significantly higher with peanut introduction between 6 and 11 months than at 4-6 months. Increasing eczema severity had limited impact on the probability of peanut tolerance in the early introduction arm.

Conclusion: Increasing peanut wheal size predicted peanut tolerance only in the avoidance arm. Peanut introduction between 6 and 11 months of age was associated with the highest rates of peanut tolerance, questioning the 'urgency' of introduction before 6 months.

Keywords: Learning Early about Peanut; allergy prevention; complementary feeding; early peanut introduction; peanut allergy.

Figure 1. Predicted Probabilities of Successful Month 60 Peanut Oral Food Challenge Among LEAP Study Participants, Based on Initial Screening Peanut Skin Test

The predicted probability for successful peanut OFC at month 60 is significantly and distinctly lower at an equivalent peanut prick skin wheal size among children randomized to the delayed introduction arm compared to the early introduction arm.

Figure 2. Predicted Probabilities of Successful Month 60 Peanut Oral Food Challenge Among LEAP Study Participants, Based on the Age of Peanut Introduction

Figure 2a demonstrates the relationship between age of peanut introduction and peanut tolerance based on the regression model in table 2a, noting a maximal probability between 6-11 months. Figure 2b details a model approximating the NIAID Guideline Addendum considerations (age, eczema severity, and peanut wheal size), which demonstrates a lower probability between 4-6 months but stable probability between 6-11 months of age compared to figure 2a.