Diagnostic utility of allergy tests to predict baked egg and lightly cooked egg allergies compared to double‐blind placebo‐controlled food challenges

Abstract

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.

Partial Egg Consumption Modifies the Diagnostic Performance of Allergy Tests to Predict Outcome of Double-Blind Placebo-Controlled Food Challenges to Egg

“…As some patients reported consuming egg in the diet when they entered the study for assessment for egg allergy we wanted to see whether egg consumption affected the results of IgE, IgG4, BAT, and SPT and whether it modified the ability of tests to predict OFC outcomes. For consumers, BAT stood out as the best test to identify patients who reacted to BE ( Figure 3 , A ); for avoiders, the best tests were BAT and sIgE to EW ( Figure 3 , B ), similar to what we observed, 12 for the whole population. Table I represents the diagnostic cut-offs for the best performer for each test modality in egg consumers and avoiders.…”

“…SPT were performed as previously described 12 using a single-head metal lancet, 10 mg/mL histamine dihydrochloride as positive control; 50% glycerol and 50% buffered saline as negative control; egg white (EW) extract (ALK Abello, Madrid, Spain), RE (using fresh raw egg white), and BE (the latter using slurry made up of 1 g of the challenge food in 10 mL of saline). We aimed to compare the degree of IgE sensitization to the various egg preparations and the utility of SPT to RE, egg extract and BE (in decreasing order of allergenicity) in supporting the diagnosis of BE and LCE allergies.…”

Precision allergy molecular diagnosis applications in food allergy

“…sIgE levels produced against ovomucoid showed the highest diagnostic accuracy for heated egg OFC [4], and were more accurate for diagnosing cooked egg allergy than those produced against egg white, ovalbumin (Gal d 2), ovotransferrin (Gal d 3), and lysozyme (Gal d 4) [5]. However, in a study regarding the diagnoses of baked egg allergy and lightly cooked egg allergy by Krawiec et al [6], egg white-sIgE, rather than ovomucoid-sIgE, had the best diagnostic accuracy. Ovalbumin is the most abundant heat-liable egg white protein [7].…”

Nasal Food Challenge with hen`s egg white allergen

“…In contrast, oral food challenge confirms sensitization to milk and fish allergens respectively at 0.9% and 0.3% of the total population [3,4,5]. The problem of allergy to hen`s egg white relates mainly to children in infancy and early childhood, in whom the prevalence of sensitization to this allergen is estimated at 16.5% [95% CI 15.1-17.9], with diagnosis being confirmed by an oral food challenge using the respective allergen in 8.9% [95% CI, 7.8-10.0] [3,6]. The problem of allergy to hen`s egg whites is also encountered within the adult population.…”

“…The latter, despite the risk of a number of adverse effects including anaphylactic shock, remains the gold standard in FA diagnostics [7,8]. In an attempt to identify alternatives to oral food allergen provocation tests, increasing attention is being paid to laboratory methods, including basophil activation tests using flow cytometry techniques [6] and nasal allergen challenge (NAC) [9,10,11,12,13,14].…”