Supplementary Material for: Clinical Features of Quail Egg Ingestion in Patients With Acquired Tolerance to Hen Eggs: A Case Series Study

Introduction Patients with hen’s egg allergy are often instructed to avoid consuming other avian eggs, such as quail eggs. However, it is unclear whether patients with an acquired tolerance to hen eggs continue to avoid consuming quail eggs. This study aimed to evaluate the clinical features of quail egg ingestion. Methods This prospective case series included children aged ≥1 year with hen’s egg allergy who were recruited between October 2019 and February 2021 in our hospital. We conducted an oral food challenge (OFC) with three boiled quail eggs to evaluate the clinical features of quail egg ingestion in patients with acquired tolerance to hen eggs. The primary outcome was a positive OFC after ingesting three quail eggs. Secondary outcomes were cross-antigenicity between hen and quail eggs observed through the skin prick test (SPT) and pattern of quail egg allergy, comprising the onset of reaction, and severity. The correlation between the diameters of the wheals with SPT in hen and quail eggs was evaluated using the Pearson product-moment correlation coefficient. Results A total of 62 patients underwent the quail egg OFC. The median (interquartile range) age of the participants was 3 (2-5) years. Thirty-three (53%) patients had a history of anaphylaxis due to hen eggs. The median total immunoglobulin E (IgE) level in patients who underwent the OFC with half a heated whole hen’s egg was 271 (98-593) IU/mL. The median specific IgE level in egg white and ovomucoid was 9.7 (3.2-21.5) and 4.4 (1.3-6.9) UA/mL, respectively. The quail egg OFC results revealed that none of the 59 patients who ate the three quail eggs completely had an allergic reaction. The SPT-positive and SPT-negative rates in raw and boiled hen and quail egg whites were both correlated. The diameters of wheals with SPT in raw hen and quail egg whites and yolks were positively correlated. Conclusion Patients with an acquired tolerance to hen eggs may not be required to avoid consuming quail eggs.