Hazelnut oral immunotherapy in children: An Italian single-center retrospective cohort study

Hazelnut oral immunotherapy (H-OIT) is a promising treatment for hazelnut allergy (HA). The aim of this study was to assess the safety and efficacy of H-OIT in a pediatric population, while describing its clinical and allergy characteristics.

Children undergoing H-OIT at our tertiary pediatric hospital Allergy Unit between April 2015 and December 2024 were enrolled. Demographic and clinical features, allergy test results and information on H-OIT were recorded.

124 patients (58.1% male; median age 8.5 years) were enrolled, 73 (58.9%) aged <4 years. The most common presenting symptom was urticaria/angioedema (75, 60.5%), followed by anaphylaxis (54, 43.5%). 54/124 (43.5%) reached the protocol's target maintenance dose within a median time of 24 months, 31/124 (25.0%) remained on a lower, partial maintenance dose at a median tolerated dose of 1000 mg of ground hazelnut. The treatment discontinuation rate was 31.5%, with over half (53.9%) due to loss to follow-up. 102/124 (82.3%) developed a reaction during H-OIT (72.5% resolved spontaneously, 14.7% occurred at home), of which 9 anaphylaxis (8.8%); only one required adrenaline, and two occurred at home because of a cofactor. Statistically significant reductions in the prick-by-prick (PbP) test diameter (p < 0.001) and Cor a 14 IgE levels (p = 0.004) were observed. A positive family history of atopy was associated with lower odds of completing H-OIT (odds ratio 0.221, 95% confidence interval 0.055-0.895, p = 0.034).

H-OIT may be an effective treatment option for children with HA despite the high discontinuation rate. One quarter of patients remained on a lower, partial maintenance dose. Although the overall safety profile of H-OIT seems acceptable, anaphylactic events represent a significant burden for families and must be carefully considered when weighing the risks and benefits of OIT.