Published Online: July 26, 2013
IgE antibody levels are widely used in the confirmatory diagnosis of food allergy. Although skin prick test (SPT) wheal sizes and serum allergen-specific IgE (sIgE) levels do not predict the severity of food-induced allergic reactions, there is evidence that they predict the likelihood of a reaction. In the past, thresholds for SPT and sIgE have been developed, above which a child has a 95% probability of having a reaction if they ingested the food, (95% positive predictive value (PPV)). However, these 95% PPVs have only been developed using high risk children and mixed age groups. This study is the first to develop 95%PPVs from a population sample with a large number of children the same age i.e. 12-month old infants, the age most likely to present for diagnosis of food allergy.
Using a population cohort of 5276 infants, Peters et al recently published in The Journal of Allergy and Clinical Immunology (JACI), SPT and sIgE thresholds with 95% PPV for challenge-confirmed peanut, egg and sesame allergy. In this study, the gold standard oral food challenge (OFC) was used to diagnose food allergy in all infants with detectable SPT, irrespective of SPT wheal size. They found that the SPT 95% PPV for peanut and sesame allergy was ≥ 8mm and egg allergy was ≥ 4mm. sIgE levels with 95% PPV to peanut allergy was ≥ 34kUA/L and egg allergy ≥1.7kUA/L.
This research is important because the prevalence of IgE-mediated food allergy in children has increased in recent decades, placing an increased demand on health services with lengthy waiting time for oral food challenges. These thresholds will be a valuable tool for the diagnosis of food allergy and will reduce the need for OFC in some children.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.