Predictors of Long-Term Desensitization in Children Treated with Oral Immunotherapy for Food Allergy: A Real-World Cohort Study

Background: The degree of desensitization achieved through oral immunotherapy (OIT) varies widely. This study aimed to identify factors predictive of full desensitization—defined as daily, symptom-free consumption of allergenic foods—in children with food allergies under real-world conditions. Methods: A follow-up survey was conducted for all children who received OIT at Mie National Hospital, Japan, between 2008 and 2017, to assess long-term safety. Patients treated for hen’s egg, cow’s milk, or wheat allergy with at least five years of follow-up were included in the analysis. Data were collected from surveys and medical records, including treatment-emergent adverse events (TEAEs), baseline allergen-specific IgE (sIgE), and daily intake of allergenic foods. TEAEs were evaluated using the World Allergy Organization grading system. Full desensitization was defined as the ability to consume a typical daily portion of the allergenic food without symptoms. Predictive factors were identified by multivariate logistic regression. Results: A total of 111 patients (142 OIT courses: egg n = 72, milk n = 47, wheat n = 23) met inclusion criteria. The median age at OIT initiation was 6 years (IQR: 5–8). No TEAEs of grade 4 or 5 were reported. Overall, 30% of them achieved full desensitization: 32% in the egg group, 24% in the milk group, and 39% in the wheat group. Low baseline sIgE and absence of mild oral symptoms during build-up were identified as significant predictors. Conclusions: Mild oral symptoms may signal lower likelihood of success. Monitoring them may support individualized OIT.