Supplementary Material for: Natural History of Allergy to Hen’s Egg: A Prospective Study in Children Aged 6 to 12 Years

Introduction: There are limited reports on the natural history of hen’s egg (HE) allergy (HEA) in children <6 years. We aimed to investigate the natural history of HEA in children aged 6–12 years and the factors affecting its tolerance acquisition. Methods: Using the database in our hospital, a total of 137 patients diagnosed with a definitive immediate-type reaction to HE when they turned 6 years were enrolled, and the natural course of HEA was prospectively examined until patients turned 12 years. Tolerance was defined as being able to pass an oral food challenge to consume a half or whole heated HE or consume heated HE freely without symptoms. Thirty patients (21.9%) who were enrolled for oral immunotherapy and 21 (15.3%) who discontinued follow-up were considered dropouts. Kaplan-Meier estimation was used to evaluate the rate of tolerance. Results: Fifty-five of the 137 patients (40.1%) had a previous HE anaphylaxis history; 61 (44.5%) patients had acquired tolerance to HE by age 12 years; and 25 (18.2%) continued total or partial HE elimination. The estimated acquired tolerance rates by ages 7, 9, and 12 years were 14.6%, 40.8%, and 60.5%, respectively. A previous history of HE anaphylaxis before 6 years of age, reacting to small amounts of heated HE by 6 years of age, and higher ovomucoid-specific immunoglobulin E values at the same age were associated with persistent HEA. Conclusion: This study provides important insights into the natural course of HEA beyond early childhood, with the acquisition of HE tolerance continuing throughout the duration of the study.