Scientific Study

BACKGROUND: Oral immunotherapy (OIT) protects patients with IgE-mediated food allergies from food-induced allergic reactions due to accidental exposure and may improve their quality of life. This approach has never been evaluated for hazelnut, a major cause of food allergy in Europe. OBJECTIVE: We sought to determine the proportion of hazelnut-desensitized patients after 6 months of OIT and to identify predictors of successful desensitization. METHOD: In a retrospective single-center study, we included patients under 18 years of age who underwent at least 6 months of hazelnut OIT for IgE-mediated allergy, defined by history of hypersensitivity reaction after hazelnut ingestion, positive hazelnut skin prick test (SPT) or specific IgE, and positive double-blind, placebo-controlled food challenge (DBPCFC). Patients able to tolerate 1635 mg of hazelnut protein (approximately 8 hazelnuts) were considered to be hazelnut desensitized. We determined the proportion of desensitized patients after 6 months of OIT, searched for associations between baseline variables and successful desensitization, and estimated the frequency and severity of OIT-related adverse reactions. RESULTS: One hundred patients were included (64% male, median age 5 years). History of severe reactions was noted in 7% of cases. At 6 months, the proportion of desensitized patients was 34% (95%CI: 25-44). The median eliciting dose (defined as the amount of hazelnut protein provoking a hypersensitivity reaction during the DBPCFC) increased from 106 mg [IQR: 51-249] at baseline to 523 mg [IQR: 190-1635] after 6 months of OIT (p<0.0001). With longer therapy, the proportion of desensitized patients increased. Using multivariate analysis, successful desensitization was associated with older age (OR: 1.5, 95%CI: 1.2-2.2), smaller hazelnut SPT wheal diameter (OR: 0.61, 95%CI: 0.4-0.8), lower hazelnut specific IgE level (OR: 0.86, 95%CI: 0.72-0.98), and absence of cashew allergy (OR: 0.42, 95%CI: 0.12-0.64). Adverse reactions occurred in 30% of patients; none were severe. CONCLUSION: In a cohort of 100 patients aged 3-9 years, our results show for the first time that hazelnut OIT is associated with hazelnut desensitization and may be safe in the majority of patients undergoing this therapy.