Background: Cow's milk is the main cause of food allergy in children. Patients allergic to food frequently experience accidental exposure. There are few studies analyzing this problem, most of them concerning peanut allergy.
Objective: We sought to calculate the frequency of accidental exposure reactions in children allergic to cow's milk during a 12-month period, to analyze the clinical characteristics and circumstances surrounding the reactions, and to identify risk factors for severe reactions.
Methods: Eighty-eight children allergic to cow's milk (44 boys; median age, 32.5 months) were included in the study. A systematized questionnaire about accidental exposure was used. Reactions were classified as mild, moderate, and severe. Cow's milk- and casein-specific IgE antibody titers were determined.
Results: Thirty-five (40%) children had 53 reactions in the previous year (53% mild, 32% moderate, and 15% severe). Most reactions took place at home (47%) under daily life circumstances (85%). Specific IgE levels to cow's milk were higher in children with severe reactions than in those with moderate (median, 37.70 vs 7.71 KUA/L; P = .04) or mild (3.37 KUA/L; P = .04) reactions. The frequency of severe reactions was 10-fold higher in asthmatic children (odds ratio, 10.2; 95% CI, 1.13-91.54).
Conclusions: Reactions to accidental exposure are frequent in children with cow's milk allergy. The proportion of severe reactions was 15%. The risk factors for such reactions included very high levels of specific IgE to cow's milk and casein and asthma.