D3.273 - Longitudinal Changes in Severity in Children with Severe, Refractory Cow’s Milk Allergy

Longitudinal data on the severity of immediate-type cow’s milk allergy are limited. We quantified oral food challenge (OFC) outcomes using the Anaphylaxis Scoring Aichi (ASCA) score and used the total score/cumulative protein dosage (TS/Pro), which incorporates the symptom-inducing threshold dose, as a severity index. Using TS/Pro, we evaluated severity trajectories over time in children with severe, refractory cow’s milk allergy.

We conducted a retrospective cohort study of children younger than 18 months (<550 days) who were judged unable to ingest 1 mL of milk by OFCs performed at our center between February 14, 2012, and November 17, 2025 (n = 117). OFCs were repeated at approximately 1-year intervals. Severe, refractory cow’s milk allergy was defined as requiring three or more OFCs before a child was judged able to ingest ≥1 mL of milk. By repeatedly checking TS/Pro of OFCs in the severe, refractory cow’s milk allergy, we observed the trajectories of severity until they became ingesting ≥1 mL of cow’s milk.

Among the 117 children in the cohort, 51 met the definition of severe, refractory allergy. Of these, 32 were included in the analysis after excluding 19 whose ability to ingest 1 mL had not been confirmed at the time of evaluation. TS/Pro decreased linearly in 14 children (43.8%), whereas 18 children (56.2%) exhibited a transient increase in TS/Pro until ingestion of ≥1 mL was achieved. The mean age when the ability to ingest ≥1 mL was confirmed was 1,551 days in the linear-decrease group and 1,698 days in the transient-increase group (p = 0.59). Among children with a linear decrease in TS/Pro, cow’s milk–specific IgE levels also showed a linear decline in 7 children (50.0%).

Two distinct patterns of severity improvement were observed in children with severe, refractory cow’s milk allergy. Improvement of the severity did not always correlate with declines in cow’s milk–specific IgE levels.