Oral food challenge (OFC) is the gold standard for the diagnosis of food allergy, but in many cases, we would reduce the OFC if we can predict the outcome of OFC. The purpose of this study was to examine the relationship between clinical characteristics and the outcome of cow’s milk (CM) OFC.
Medical records of 44 children who underwent CM OFC, from January 2013 to March 2015 at Ajou University Hospital, were reviewed. Data were analyzed to determine the relationship between OFC outcome and clinical parameters, including specific IgE (sIgE) levels to milk and casein measured before OFC.
Twenty-nine of 44 patients (65.9%) were male, and the mean age was 3.3 years (6-177.6 months) with 95.5% aged 12 months or over. Thirteen had no history of CM ingestion and 31 had previous history of immediate reactions after CM ingestion (OFC performed for detection of clinical tolerance). Among them, 64.5% reported acute urticaria and 32.3% experienced anaphylaxis at initial CM ingestion. The number of subjects who passed OFC (successfully ingested cumulative dose of 200 mL of CM without allergic reactions, Group P) was 30 out of 44 (68.2%). Among the 14 children who failed OFC (Group F), cutaneous symptoms were reported in 100%, while upper respiratory, lower respiratory and gastrointestinal symptoms were noted in 35.7%, 7.1% and 14.3%, respectively. Seven patients experienced anaphylaxis (three of them with anaphylaxis history on initial CM ingestion) but none of them had cardiovascular or nervous symptoms during OFC. The median cumulative dose of CM at symptom onset during OFC was 22.0 mL. The median level of milk-sIgE in Group F was higher than that in Group P (5.04 kUA/L vs 1.42 kUA/L, p = 0.003), and the median level of casein-sIgE in Group F was also higher than that in Group P (7.56 kUA/L vs 0.53 kUA/L, p=0.003). Using receiver operating characteristic curves, the optimal cutoff points for milk-sIgE and casein-sIgE in children aged 12 months or over, were 1.71 kUA/L and 7.00 kUA/L, respectively. The number of subjects younger than 12 months was only two, so the optimal cutoff points in this group were not obtained. Initial levels of milk-sIgE and casein-sIgE, age at OFC, and anaphylaxis at initial CM ingestion were not significantly related with the outcome of OFC. Past history of asthma was a significant factor associated with increased risk of OFC failure (p=0.045) in crude analysis, but the relation was not significant after adjustment with confounding factors.
The levels of sIgE to milk and casein were significantly higher in patients who failed CM OFC compared to those in cases who passed OFC. The cutaneous symptoms occurred in all patients who failed OFC, and 7 patients experienced anaphylaxis during OFC. The comorbidity of asthma was the only significant factor associated with increased risk of OFC failure in crude analysis.