Is Ara h 2 indeed the best predictor for peanut allergy in Dutch children?

Background: Specific immunoglobulin E to Ara h 2 (sIgE to Ara h 2) is described as an upcoming predicting factor for diagnosing peanut allergy in children. The gold standard for diagnosing peanut allergy is a double blind placebo controlled food challenge, however this is time consuming and potentially harmful. We investigate Ara h 2 as a preliminary less invasive diagnostic tool for diagnosing peanut allergy in a general population of peanut sensitized children. Methods: Children (n = 52) with peanut sensitization were retrospectively included. An oral food challenge (OFC) confirmed peanut allergy or tolerance, as primary outcome. Individual candidate predictors were identified by univariate regression analysis and used in a prediction model. Different cut-off values were obtained and receiver operating characteristic curves were plotted. Results: Multivariate analyses resulted in Ara h 2 as best predictor, with a discriminative ability of 0.87 (95% confidence interval, 0.77-0.97). Sensitivity and specificity of 55% and 95%, respectively, were found for a sIgE to Ara h 2 cut-off value of 4.25 kU/L. The highest positive predictive value of 100% was reached at 5.61 kU/L. No absolute relation was found between the value of Ara h 2 and the severity of the reaction during OFC. Conclusion: This study developed a prediction model in which sIgE to Ara h 2 was the best predictor for peanut allergy in sensitized children in a general hospital. Therefore depending on the history and the Ara h 2 results, an OFC is not always needed to confirm the diagnosis.