Children 4 to 11 months of age who were at high risk for development of peanut allergy were assigned to consumption or avoidance of peanuts until 60 months of age. Peanut allergy was more than five times as likely to develop in children assigned to peanut avoidance. (View a 1-minute Video Summary. And, ask the authors and experts about the study in the NEJM Group Open Forum on Medstro.com.)
Several years ago, the Learning Early about Peanut Allergy (LEAP) researchers found that the risk of the development of peanut allergy was 10 times as high among Jewish children in the United Kingdom as it was in Israeli children of similar ancestry. This observation correlated with a striking difference in the time at which peanuts are introduced in the diet in these countries: in the United Kingdom infants typically do not consume peanut-based foods in the first year of life, whereas in Israel, peanut-based foods are usually introduced in the diet when infants are approximately 7 months of age. The LEAP trial was conceived to determine whether the early introduction of dietary peanut could serve as an effective primary and secondary strategy for the prevention of peanut allergy.
- Is there evidence that eliminating allergenic foods from the diets of infants can prevent future allergy?
Clinical practice guidelines from the United Kingdom in 1998 and from the United States in 2000 recommended the exclusion of allergenic foods from the diets of infants at high risk for allergy and from the diets of their mothers during pregnancy and lactation. However, studies in which food allergens have been eliminated from the diet have consistently failed to show that elimination from the diet prevented the development of IgE-mediated food allergy.
- Does peanut consumption as compared with peanut avoidance decrease peanut allergy in at-risk infants with no preexisting peanut sensitivity?
The study by Du Toit et al. included infants aged 4 to 11 months who had severe eczema, egg allergy, or both. Among the 542 infants in the group with a negative result on an initial skin-prick test assessing preexisting peanut sensitivity, 530 (97.8%) could be evaluated for the primary outcome and were included in the intention-to-treat analysis. At 60 months of age, 13.7% of the avoidance group and 1.9% of the consumption group were allergic to peanuts; this absolute difference in risk of 11.8 percentage points (95% confidence interval [CI], 3.4 to 20.3; P<0.001) represents an 86.1% relative reduction in the prevalence of peanut allergy.
Morning Report Questions
Q: Does peanut consumption as compared with peanut avoidance decrease the development of peanut allergy in at-risk infants who have preexisting peanut sensitivity?
A: All 98 children in the group with positive results on the initial skin-prick test were evaluated and were included in the intention-to-treat analysis. At 60 months of age, 35.3% of the avoidance group and 10.6% of the consumption group were allergic to peanuts; the absolute difference in risk of 24.7 percentage points (95% CI, 4.9 to 43.3; P=0.004) represents a 70% relative reduction in the prevalence of peanut allergy.
Figure 2. Primary Outcome.
Q: How do levels of peanut-specific IgE, IgG, and IgG4 in infants who consume peanuts compare to those of infants who do not consume peanuts?
A: At 60 months, the number of participants with markedly elevated levels of peanut-specific IgE titers was higher in the peanut-avoidance group than in the consumption group. In contrast, the peanut-consumption group showed a significantly greater and earlier increase in levels of peanut-specific IgG and IgG4; this effect mirrors the immunologic changes seen in successful allergen immunotherapy. Furthermore, in the avoidance group, unless peanut-specific IgE levels were very high, elevated IgG4 levels were associated with the absence of an allergic reaction to peanuts. Both observations indicate that IgG4 is associated with a protective role against the development of allergy.