BackgroundDouble‐blind placebo‐controlled food challenges (DBPCFC) are the gold‐standard to diagnose food allergy. However, they can cause allergic reactions of unpredictable severity. We assessed accuracy of current and new diagnostic tests compared to DBPCFC to baked egg (BE) and to lightly cooked egg (LCE).MethodsChildren aged 6 months to 15 years were assessed for possible egg allergy as part of the BAT2 study (NCT03309488). They underwent clinical assessment, skin prick test (SPT), specific IgE (sIgE) and basophil activation test (BAT). The results of the tests were compared with DBPCFC outcomes to both BE and LCE.ResultsA total of 150 children underwent DBPCFC to BE, 60 (40%) reacted to and 85 (57%) tolerated BE and 5 (3%) had inconclusive oral food challenges (OFC). Seventy‐seven children tolerant to BE had DBPCFC to LCE and 16 reacted. The test within each modality with the best diagnostic performance for BE allergy was as follows: SPT to egg white (EW) (AUC = 0.726), sIgE to EW (AUC = 0.776) and BAT to egg (AUC = 0.783). BAT (AUC = 0.867) was the best test in the younger than 2 years age group. Applying 100% sensitivity and 100% specificity cut‐offs, followed by OFC, resulted in 100% diagnostic accuracy. BAT enabled the greatest reduction in OFC (41%). Using sIgE followed by BAT allowed to reduce the number of BATs performed by about 30% without significantly increasing the number of OFC.ConclusionsThe best diagnostic test was BAT to egg in terms of diagnostic accuracy and reduction in number of OFC. Using sIgE to EW followed by BAT required fewer BATs with sustained OFC reduction and diagnostic accuracy.

Food allergy has recently become more common. There is no curative treatment for food allergy and management relies on allergen avoidance and emergency treatment of accidental allergic reactions. Food allergy can have a significant impact on the lives of patients and their families and an accurate diagnosis is, therefore, of utmost importance. A food allergy‐focused clinical history, together with evidence of allergen‐specific IgE, can be enough to confirm or exclude the diagnosis of food allergy; however, in the equivocal cases, exposure to the allergen in a controlled environment in hospital, called oral food challenge (OFC), is required. New tests are being developed to reduce the number of patients that need OFCs. Allergen‐specific immunotherapy has shown to reduce patients' sensitivity to the allergen but the majority of treated patients still remain food allergic. In the absence of a definitive treatment, prevention of food allergy is key. Key Concepts Food allergy prevalence is increasing, affecting about 7% of children and 2% of adults, with cow's milk, egg, peanut, tree nuts, sesame, fish and shellfish constituting more than 90% of food allergies in children. Risk factors for food allergy are atopic eczema, family history of atopic diseases, black or Asian ethnicity, less diverse diet, low serum vitamin D and filaggrin loss‐of‐function mutations. The diagnosis of food allergy is usually based on a combination of clinical history and evidence of allergen‐specific IgE, with oral food challenges being reserved for the equivocal cases. There is no curative treatment for food allergy; management consists of allergen avoidance and emergency treatment plan for accidental allergic reactions. Allergenic foods should be introduced in the diet at the time of weaning. Early peanut consumption in the first year of life can prevent the development of peanut allergy at school age.

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