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

## TL;DR

This study examines the safety and effectiveness of hazelnut oral immunotherapy in children, finding it promising but with notable challenges like high discontinuation rates.

## Contribution

The study provides real-world data on H-OIT in a large pediatric cohort, highlighting its clinical outcomes and safety profile.

## Key findings

- 43.5% of patients reached the target maintenance dose within 24 months.
- 25% of patients remained on a lower, partial maintenance dose.
- Anaphylactic events occurred in 8.8% of patients, emphasizing safety concerns.

## Abstract

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.