Scientific Study

BACKGROUND: The rise in peanut allergy is a source of considerable burden in the community. A growing number of pre-schoolchildren have been identified as peanut sensitized in the course of investigation of other allergic conditions. Although many have never knowingly ingested peanuts and their clinical reactivity is not known; it has been common practice to place these children on avoidance diets for many years. OBJECTIVE: To determine the utility of skin prick tests (SPT) and fluorescent-enzyme immunoassays (FEIA) for identifying either peanut allergy or tolerance in pre-schoolchildren with peanut sensitization. METHODS: Forty-nine pre-schoolchildren (<5 years of age) with peanut sensitization (SPT 2 mm or peanut-specific IgE 0.35 kU/L) but unknown clinical reactivity had graded open peanut challenges reaching a total of 11g. A positive challenge was defined as an objective IgE-mediated reaction during challenge or the 2-h observation. Results Forty-nine percent (24/49) of children had positive challenges. An SPT of > 7 mm on the day of challenge predicted a positive challenge with a sensitivity of 83% and a negative predictive value (NPV) of 84%. An FEIA of > 2.0 kU/L showed a sensitivity of 79% and an NPV of 80%. Predicting challenge outcome from a combination of SPT and FEIA (SPT > 7 and/or FEIA > 2 is positive) increased sensitivity to 96% and NPV to 95%. CONCLUSION AND CLINICAL RELEVANCE: At least half of pre-schoolchildren with peanut sensitization and no antecedent history of peanut ingestion can tolerate peanuts. A SPT<7 mm and FEIA < 2 kU/L identify children most likely to tolerate peanut; with only a 5% likelihood of failing an oral challenge. This study assists clinicians considering challenges in very young peanut-sensitized children.