Hen's Egg Allergy is one of the most common food allergies in early childhood. The first-line treatment is the elimination of hen's egg proteins from the child's or maternal diet.

Available data from the literature indicate that most children with hen's egg allergy acquire tolerance to hen's egg proteins with age. An assessment of tolerance acquisition to them is commonly performed using egg ladder. However, scientific evidence regarding the effectiveness and safety of the egg ladder in children with hen's egg allergy is limited. Currently, there is no standardised egg ladder protocol, and different versions of the ladder and recommend by scientific societies in various countries.

This study aims to assess the effectiveness and safety of the 4-step egg ladder (4-EL) compared to the 5-step egg ladder (5-EL) in children with IgE-mediated hen's egg allergy. This is an open-label, randomised superiority trial with two parallel arms and a 1:1 allocation ratio.

Introducing baked egg into the diet of children with hen's egg allergy has been shown to potentially accelerate the development of tolerance to raw egg. However, there is no standardised egg ladder protocol, and different scientific societies across countries recommend varying versions.

This study aims to assess the effectiveness and safety of the 4-step egg ladder (4-EL) compared to the 5-step egg ladder (5-ML) in children with IgE-mediated hen's egg allergy.

An open-label randomised trial with two parallel arms in two departments of the same academic hospital will be performed. A total of 84 children with IgE-mediated hen's egg allergy will be allocated to introduce hen's egg into their diet according to either 4-EL or 5-EL with a 6-week break period between subsequent steps. Oral food challenge (OFCs) with tested products at each subsequent step of the egg ladder will be conducted in hospital settings. The primary outcome is the percentage of children who acquire tolerance to soft-boiled hen's egg (almost raw hen's egg proteins), as determined by a negative OFC at the final step of the EL. Soft-boiled egg will be administered at the end of the observation period (18 or 24 weeks, depending on the assigned study arm). The challenge dose will consist of 0,5-1 egg for children aged 1-3 years and 1 egg for those aged 4-5 years, corresponding to a maximum total of 6 g of hen's egg proteins.

Secondary outcomes will include the percentage of children with a negative OFC to each egg ladder step; the percentage of children with anaphylaxis (both those who were treated and who were not treated with adrenaline); the percentage of children with exacerbation of atopic dermatitis; growth; compliance; and quality of life of the caregivers and parents' anxiety about adverse events during their child's OFC.

The statistical analyses will be conducted with StatsDirect. The Mann-Whitney U test will be used to compare the means of continuous variables if non-normal distribution will be assessed. Proportions will be compared with the Fisher exact test. The difference in study groups was considered significant when the P value will be <05. The results of this study will be analyzed on the basis of intention to treat.

Inclusion Criteria:

• Age ≥ 12 months and ≤ 5 years.
• Diagnosis of IgE-mediated HEA confirmed according to the EAACI guidelines by a positive OFC with hen's egg proteins. In children with high-risk HEA (e.g., history of anaphylaxis), diagnosis can be based on elevated specific IgE levels (3.5 kU/l) to hen's egg proteins and/or individual egg components and/or positive skin tests.
• On a therapeutic elimination diet for at least 6 months, measured from the last allergic reaction to egg (in accordance with BSACI guidelines).
• Eligible regardless of the risk of systemic reactions (e.g. anaphylaxis) or asthma.
• Good general health.
• Written informed consent signed by the child's guardians.
• Demonstrated good cooperation from the patient's guardians.

Exclusion Criteria:

• Confirmed wheat allergy and/or celiac disease.
• Uncontrolled asthma, defined as the presence of shortness of breath, cough, chest tightness, or auscultatory changes despite treatment.
• Signs of exacerbation of a chronic disease.
• Signs of acute infectious disease (e.g. acute rhinitis, cough, subfebrile or febrile states).
• Signs of exacerbation of another allergic disease (e.g., conjunctivitis, allergic rhinitis, atopic dermatitis).
• Anaphylaxis due to hen's egg proteins within the last 6 months.
• Use of antihistamines within 3-10 days before the challenge (depending on the drug and indication; time-limited contradiction - relative exclusion criterion).
• Acquired tolerance to baked hen's egg proteins or advancement to a higher step of the egg ladder.
• Use of immunosuppressive drugs or immunotherapy.

The results of this RCT, whether positive or negative, will be published in a peer-reviewed journal (data will be submitted to the first journal after 3-6 months from study completion). Abstracts will also be submitted to relevant national and international conferences.

The datasets used and/or generated during this study will be made available from a given author upon reasonable request, after the publication of results, no later than 3 years from the completion of data analysis.

After the publication of results, no later than 3 years from the completion of data analysis with no end date.

Upon reasonable request.