High-Risk Infant Definition for Peanut Allergy
A high-risk infant for peanut allergy is defined as one with severe eczema, egg allergy, or both, occurring in the first 4-6 months of life. 1, 2
Severe Eczema Criteria
An infant meets the severe eczema threshold when they have an eczematous rash that fulfills BOTH of the following requirements: 1
Requires topical corticosteroids or calcineurin inhibitors for treatment, with the rash lasting at least 12 of 30 days on 2 separate occasions 1, 2
- For infants <6 months: This pattern must occur at any point
- For infants ≥6 months: This pattern must occur within the last 6 months
Modified SCORAD score >40 (either currently or previously documented) 1
Important clinical note: The severity and duration of topical treatment requirement is the key distinguishing feature—mild eczema that resolves quickly or requires only intermittent moisturizers does not qualify as high-risk. 1
Egg Allergy Criteria
An infant is considered high-risk if they have documented egg allergy defined by EITHER: 1
Skin prick test (SPT) wheal diameter >6 mm to raw hen's egg white AND no history of previous egg tolerance 1
SPT wheal diameter >3 mm to pasteurized hen's egg white AND documented allergic symptoms related to egg exposure 1
Critical distinction: Egg allergy must be diagnosed in the first 4-6 months of life to qualify the infant as high-risk for peanut allergy. 1, 2
Risk Stratification Beyond the LEAP Criteria
Recent research has identified additional factors that increase peanut allergy risk within the high-risk population: 3
- Older age at introduction (even within 4-11 months): Each additional month of age increases odds of peanut allergy by 30% (OR 1.3 per month) 3
- Higher SCORAD scores: Each 5-point increase in SCORAD score increases odds by 19% (OR 1.19) 3
- Black or Asian race: Black infants have 5.8-fold increased odds, Asian infants have 7-fold increased odds compared to white infants 3
- Presence of another food allergy: Increases odds 4-fold (OR 3.98) 3
What Does NOT Constitute High Risk
Family history alone (first-degree relative with peanut allergy) without eczema or egg allergy does NOT qualify an infant as high-risk. Only 1% of infants with family history but no eczema developed peanut allergy, compared to 18% with eczema. 3 The NIAID guidelines and subsequent consensus statements do not recommend screening or special precautions for infants with family history alone. 1, 2
Mild-to-moderate eczema that does not meet the severe criteria above places infants in an intermediate-risk category, not high-risk, and these infants should introduce peanut around 6 months without prior testing. 1
Clinical Management Implications
High-risk infants should be evaluated by an allergist or appropriately trained physician between 4-6 months of age before peanut introduction. 1, 2 This evaluation should include skin prick testing (NOT serum IgE, which has considerably higher false-positive rates leading to unnecessary oral food challenges). 1, 2
The evidence supporting this definition comes from Level 1 evidence (the LEAP trial), which demonstrated up to 80% reduction in peanut allergy when high-risk infants introduced peanut early. 1, 2