D2.297 - Assessing thresholds for undertaking baked milk food challenges

The prevalence of cow’s milk allergy is up to 7.5% in the first year of life. Allergies to cow’s milk cause a large burden to families and impact on growth and nutrition of children. There is also a significant cost to healthcare. Development of oral immunotherapy is likely to change how we manage milk allergy in the future. Thresholds for decisions around undertaking baked milk challenges vary significantly and there is a wide range of clinical practice.

This project aimed to review thresholds for performing baked milk food challenges based on clinical history, skin prick tests and specific IgE blood results and review the outcomes of these baked milk challenges. 

Baked milk food challenges which occurred from 2023 to September 2025 at University Hospitals Bristol and Weston were reviewed. The challenge outcomes, skin prick test results and specific IgE to milk for all completed challenges were recorded. Positive and inconclusive challenges were reviewed to determine allergic reaction details as per the PRACTALL scoring system. The clinical history was also reviewed to determine high risk factors including anaphylaxis, multiple allergies, asthma and eczema.  

55 baked milk challenges occurred between 2023 and September 2025. The average age of child was 6.  87% (n=48) of challenges were negative (no reaction during challenge), 4% (n=2) were positive (allergic reaction during challenge) and 9% (n=5) were inconclusive. Of inconclusive tests 80% (n=4) were due to refusal of eating further doses, rather than concern of a clinical reaction. 20% (n=1) was due to a grade 1 mild skin reaction.

The two positive challenges consisted of grade 1 gastrointestinal reactions. In both positive challenges there was a clinical history of anaphylaxis, wheeze and eczema. In one case there were multiple food allergies. Positive challenges had skin prick test results of 10 and 6mm and did not have specific IgE bloods sent.

Of negative challenges, 100% (n=48) had a skin prick test of 3mm or above. 48% (n=23) had a skin prick test of 10mm or above. There was a very wide range of specific IgE blood results in the negative challenges (see figure 1). 

In conclusion, the clinical history of high-risk features such as previous anaphylaxis and allergic co-factors may be more significant in predicting outcomes from baked milk challenges, compared to skin prick testing and specific IgE blood results. More information on positive challenges to baked milk is required to determine this.