Cut-off values and thresholds of allergic reaction during oral food challenge: a retrospective study

Levina, Daria

Cut-off values and thresholds of allergic reaction during oral food challenge: a retrospective study

Thesis / Dissertation

2025

Publisher

University of Cape Town

Department

Department of Paediatrics and Child Health

Faculty

Faculty of Health Sciences

Abstract

Food allergy (FA) negatively impacts the quality of life of millions of people and represents a substantial physical and economic burden for the patient, his family, and the state. The gold standard for food allergy diagnosis worldwide is the oral food challenge (OFC). However, data on the OFC threshold and the efficiency of tests used for FA diagnosis in the South African population are lacking. Methods: A retrospective analysis of all the OFCs carried out at the Red Cross War Memorial Children's Hospital, University of Cape Town, from 2015 to 2023 was performed. Data on the type of food used, OFC outcome, the cumulative amount of protein taken, and data from the previous allergic assessment (skin prick test, specific IgE and components results) were collected. Results: Of the 223 oral food challenges conducted, 61% were negative, 36% were positive, and 2% were indeterminate. Diagnostic test performance varied by allergen, with internationally derived cut-offs often demonstrating suboptimal sensitivity. For cow's milk, the fresh skin prick test (SPT) (≥4 mm) showed high sensitivity (100%) and specificity (83.3%), whereas commercial SPT (≥8 mm) had poor sensitivity (0%). Ara h2-specific IgE (sIgE) outperformed peanut sIgE (AUC 0.785 vs. 0.635). ROC analysis identified lower optimal cut-offs for sIgE, improving diagnostic accuracy. Eliciting dose thresholds varied with age, with younger children exhibiting lower thresholds for cooked eggs and peanuts. Conclusion: These findings highlight the need for population-specific diagnostic thresholds and age- adjusted risk assessments. Lower diagnostic cut-offs improved test performance, and younger children exhibited lower eliciting dose thresholds for certain allergens. These findings emphasize the importance of refining allergy testing protocols to balance safety with minimizing unnecessary dietary restrictions.

Keywords

Food allergy

Children

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Masters

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