Added diagnostic value of peanut component testing : a cross-sectional study in Australian children

Background: Peanut components are widely used in clinical practice; however, their utility to predict challenge outcome in the Australian children, outside of infants, is not well studied. Objective: Can peanut component testing predict outcome of challenge in peanut-allergic children. Methods: All children attending peanut challenges, regardless of previous allergic reactions to peanut or sensitization (skin prick test or peanut IgE) alone, were recruited. Serum collected before the challenge was analyzed for peanut IgE and Ara h 1, 2, 3, 6, 8, and 9 (ImmunoCap). Results: Of the 222 children recruited, 89 (40%) were allergic on oral food challenge. Ara h 2 and 6 performed similarly to peanut IgE and skin prick test in predicting challenge outcome (area under the curve, 0.84-0.87). No baseline clinical characteristics, including past history, predicted challenge outcome. By logistic regression, degree of polysensitization to Ara h 1, 2, or 3 increased the odds of allergic reaction at oral food challenge at 0.35 and 1.0 kUA/L cutoff levels (P <.001 for both). All 11 children sensitized (>0.35 kUA/L) to Ara h 1, 2, and 3 reacted to peanut challenge. Degree of polysensitization at more than 1.0 kUA/L was associated with a lower cumulative eliciting dose (P =.016) and with severity of allergic reaction on challenge (P =.007). Conclusions: In our cohort, sensitization to the combination of Ara h 1, 2, and 3 was highly predictive of peanut allergy. Overall, only Ara h 2 as individual component most correlated with severity of reaction at challenge and adrenaline use. Ara h 8 and 9 were not useful in predicting challenge outcome.