Defining the Window of Opportunity and Target Populations to Prevent Peanut Allergy

There are ongoing efforts to prevent peanut allergy, as it affects 1% to 2% of children and up to 18% of infants with moderate to severe eczema. The purpose of this study is to determine the optimal timing of peanut introduction in targeted groups within the general population.

The analysis included patient outcome data from merging 3 studies: the Inquiring About Tolerance study, Learning About Peanut Allergy (LEAP) study, and Peanut Allergy Sensitization study. In total, the study population included 2137 children aged 3 to 11 months at inclusion, ranging from low risk to very high risk for peanut allergy. The Inquiring About Tolerance study consisted of 1303 normal risk breastfed infants randomized to exclusive breastfeeding or early introduction of 6 foods (including peanut). The LEAP study included 640 high risk patients with severe eczema, egg allergy, or both, and either negative or positive but small (<4 mm wheal) skin prick testing to peanut who were randomized to early peanut introduction or avoidance. The Peanut Allergy Sensitization study was composed of a combined 194 low risk (no eczema or egg allergy) and very high risk (concomitant severe eczema, egg allergy, and large peanut skin test size) infants from the LEAP screening trial.

This study used the established data to model peanut allergy across different cohorts of populations with varying risk levels. A logistic regression was used to estimate the LEAP trial intention-to-treat intervention effect that represents allergy reduction with conditional peanut introduction in the first year of life versus avoidance until age 5 years. This effect was then used to model prevalence of peanut allergy at age 5 years when applied at different time points across stratified populations.

Based on these models, early introduction of peanut products reduced peanut allergy by 4.6% at 5 years of life when applied to only the highest risk infants with severe eczema. However, much greater reductions in estimated peanut allergy were observed when applied to the larger, lower risk groups. There was an estimated total 77% risk reduction in peanut allergy at age 5 years with peanut product introduction at age 4 months for infants with severe eczema and/or egg allergy and at 6 months for infants without severe eczema or egg allergy. The risk reduction of peanut allergy decreased with each month of delayed introduction, with an estimated 33% reduction of peanut allergy with peanut introduction to all infants at age 12 months. The negative impact of delayed introduction of peanut was also most marked in infants with increasing eczema severity.

The greatest benefit in reduction of peanut allergy occurs with early introduction of peanut products at age 4 to 6 months and when applied to all infants (as opposed to only those at high risk). In addition, there is decreasing benefit with each month of delay in peanut introduction.

In 2017, the National Institute of Allergy and Infectious guidelines recommended introduction of peanut at age 4 to 6 months for infants with egg allergy or severe eczema, around 6 months for infants with mild-moderate eczema, and at an age-appropriate time for other infants. However, those guidelines were based on expert opinion and extrapolated from data from the LEAP trial that had targeted high risk populations. This study uses a more robust data set to demonstrate the predicted benefit of early introduction of peanut for all infants, portraying maximal prevention of peanut allergy with peanut product introduction starting at age 4 months for infants with severe eczema and by 6 months for all infants.