The natural history of cow's milk allergy in north-eastern Poland.

Purpose: The rate of cow's milk allergy diminishes with age. There is not enough information concerning geographical trends in persistent cow's milk allergy in children. The objective of the study was to evaluate the prevalence of persistent cow's milk allergy in children previously diagnosed with IgE-mediated cow's milk allergy (CMA).

Material/methods: Diagnosis of cow's milk allergy was established by a medical history of symptoms associated with exposure to cow's milk, positive skin prick tests with cow's milk, the presence of milk-specific IgE, and by a positive double- or single-blind placebo-controlled food challenge with milk confirmed by a positive open-controlled milk challenge. A second oral challenge was performed after at least one year of a milk-free diet and children with a positive oral milk rechallenge were diagnosed as having a persistent CMA.

Results: Two hundred ninety-one children, 2-14 years of age (mean 5.30±3.16 years, 95% CI, 5.02-5.62 years) completed the study. Persistent CMA was diagnosed in 79 patients (27.1%). Two hundred twelve children (72.9%) outgrew their allergy to cow's milk at a mean age of 5 years after an average time of 16.4±0.8 months on an elimination diet. Eighty percent of children below 3 years of age became milk tolerant. Milk-specific IgE (p=0.018) and history of paternal bronchial asthma and/or rhinitis (p=0.020) were associated with persistence of cow's milk allergy in regression analysis.

Conclusions: An age above 3 years, as well as features of atopy, individual and familial, may be associated with a risk of delayed tolerance to milk in children.