PURPOSE OF THE STUDY.
The investigators determined the prevalence of cow milk allergy, the cross-reactivity with soy, and risk factors for the development of cow milk allergy in a large-scale, population-based prospective study.
All infants (13 234) born from June 10, 2004, to June 30, 2006, at the Assaf-Harofeh Hospital in Zerifin, Israel, were eligible for enrollment. The feeding history was obtained for 98.4% (13 019) of these infants, mostly by telephone interview.
In the newborn period, after routine anticipatory guidance, in which breastfeeding was encouraged and other alternative cow milk–based feeding programs were reviewed, parents were asked to either fill in a questionnaire or contact the allergy clinic immediately after any suspected adverse reaction to the initiation of cow milk–protein feeding. If no unusual event was noted, the families were asked to contact the allergy clinic 14 to 30 days after initiation of cow milk–based feeding. Any parents who noted a possible adverse reaction were interviewed by an investigator and invited for examination and testing. Final diagnosis of immunoglobulin E (IgE)-mediated cow milk–protein allergy was made independently by 2 investigators, and any disagreement (2 cases) was resolved with conjoint discussion. Skin-prick testing to cow's milk and soy was conducted, as were open cow milk challenges.
The cumulative incidence of IgE-mediated cow milk allergy was 0.5% (66 of 13 019). The mean age of cow milk introduction was significantly different (P < .001) between healthy infants (61.6 ± 92.5 days) and those with IgE-mediated cow milk allergy (116.1 ± 64.9 days). Only 0.05% of the infants who were started on regular cow milk–protein formula within the first 14 days versus 1.75% who were started on formula between the ages of 105 and 194 days had IgE-mediated cow milk allergy (P < .001). None of the patients with IgE-mediated cow milk allergy proved to have an IgE-mediated soy allergy.
In this patient population, IgE-mediated cow milk allergy is less prevalent than previously reported. Early exposure to cow milk protein seemed to be protective against cow milk allergy.
The results of this study, as well as those of other recent investigations, go against the previous mantra that prolonged restriction of specific food allergens might be helpful in the prevention of food sensitivity in the early years. Early introduction of specific dietary proteins seems to lead to tolerance, although the exact timing and dose required have not been determined. It is remarkable that none of the subjects with IgE-mediated milk allergy proved to have soy allergy, contrary to a reported co-reactivity of 10% to 14%. Because the reported rate of IgE-mediated milk allergy is lower in this study population than has been reported previously, additional studies are required to confirm these findings.
- Copyright © 2011 by the American Academy of Pediatrics