The predictive value of specific immunoglobulin E on the outcome of milk allergy.

BACKGROUND Cow's milk allergy is the most prevalent food hypersensitivity, affecting 2-3% of infants, but it tends to resolve with age. Cow's milk-specific immunoglobulin E in the serum is an important measure in the diagnosis and follow-up of infants and children with cow's milk allergy. OBJECTIVES To examine the relation between CmsIgE and the probability of resolution of milk allergy. METHODS CMsIgE was determined in the serum of 1800 infants and children referred for the evaluation of possible milk allergy. All children with CmslgE of 1 kU/L or above were followed at the allergy clinic and, according to their condition, underwent milk challenge. The diagnosis of cow's milk allergy was made on the basis of a significant and specific history or a positive oral food challenge. Subsequently, oral tolerance was defined as an uneventful oral challenge. RESULTS A total of 135 infants and children had milk-specific IgE greater than 1 kU/L. Forty-one percent of children still had clinical milk allergy after the age of 3 years. Sixty-eight percent of children older than 3 years with persistence of cow's milk allergy had milk-specific IgE > 3 IU/ml before the age of 1 year. Furthermore, 70% of children who at 3 years old had resolved their cow's milk allergy had milk-specific IgE that was lower than 3 IU/ml before the age of 1 year. The positive predictive value of CmsIgE > 3 IU/ml to persistent cow's milk allergy at age 3 years was 82.6% (P = 0.001), with a sensitivity of 67.9% and specificity of 70.4%. CONCLUSIONS Milk-specific IgE concentration in the first year of life can serve as a predictor of the persistence of milk allergy.