[Clinical features of children with cow's milk sensitization]

Objective: To investigate sensitization rate of cow's milk in children, and explore its clinical features. Methods: This study enrolled a total of 818 patients under 18 years old with suspected food allergy who were admitted to the Allergy department in Beijing Shijitan Hospital during June 2018 to November 2020. The ImmunoCAP fluorescent enzyme-linked immunoassay system was used to quantify cow milk-specific immunoglobulin E (sIgE). Mild sensitization to cow's milk was defined as Radio-Allergo-Sorbent-Test (RAST) class 1, moderate sensitization was defined as class 2-3 and severe sensitization was class 4-6. Statistical methods such as χ² test, independent sample t-test, one-way analysis of variance, and Spearman correlation analysis were used to retrospectively clarify differences of cow's milk sensitization rate between ages of children and elaborate its clinical features. Results: Overall sensitization rate of cow's milk reached 25.7% (210/818). Positive rate of cow milk sensitization (39.2%), cow milk sIgE levels [0.93 (0.52, 2.62)] kU/L, and moderate to severe sensitization rate (23.5%) were highest in infants aged between 0-3 years old. The sensitization rate and severity of sensitization declined with age. Most common clinical manifestation of cow milk sensitization was skin symptoms (50.0%), followed by respiratory symptoms (38.9%) and gastrointestinal symptoms (36.1%). Skin symptoms were the most common manifestation in 0-3 year-old group (47.3%), and respiratory symptoms were more common in 4-6 and 7-18 year-old groups (58.7%, 56.0%). Multiple-sensitization rate of patients with moderate to severe cow milk sensitization was 74.1%, most of which (70.4%) were co-sensitized by other food allergens, and 31.5% were co-sensitized by inhaled allergens. Conclusions: In population with age under 18 years old, infants aged between 0-3 years old suffered highest cow milk sensitization rate and increased sensitization severity. Then the severity decreased with age increasing. Patients with cow milk sensitization manifested skin symptoms most.