SAN FRANCISCO – Baseline milk-IgE level and skin-prick wheal size do a good job of predicting if a child will outgrow a milk allergy, but variation in eczema severity does not, two studies have shown.
"If you have a low milk-specific IgE, less than 2 on the ImmunoCAP test, about [65%] of babies outgrow their allergy" by 30 months. "If you look at those with higher numbers, greater than 10, only 7% of those babies outgrow their allergy," said lead investigator Dr. Robert A. Wood, professor of pediatrics and chief of the division of allergy and immunology at Johns Hopkins Children’s Center, Baltimore.
In the eczema study, "what we found was that the more severe the eczema you had when you came into the study, the less chance of outgrowing your milk allergy," but reduction in eczema severity did not correlate with milk allergy resolution, said Dr. Wood, also an investigator on the second trial.
Being able to predict resolution is important not only to reassure parents and guide treatment, but also because immunotherapy desensitization techniques being developed by Dr. Wood and others may be widely available in 5 or 10 years.
"If we have a marker that says this child can do it on their own by the time they are 2½, that’s great. If we have a marker that says this child will have a lifetime milk allergy, and maybe [immunotherapy] will be most effective if we initiate it early, that will be an incredibly important piece of information," he said at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.
Populations for both studies were drawn from the Consortium of Food Allergy Research (CoFAR) cohort, a National Institutes of Health–funded project with more than 500 children.
In the first study, 89 (36.5%) of 244 milk-allergic infants aged 3-15 months tolerated milk by month 30. The median age of resolution was 2 years.
Those who outgrew their allergy started the trial with a median baseline milk-IgE of 0.72 kU/L; those who did not started with a median of 6.99 kU/L. Only 14.2% of infants who entered the trial with IgE values at or above 5 kU/L resolved their allergy by month 30.
Also associated with resolution was a median baseline milk skin-prick wheal size of 5.0 mm. The median size of those who remained allergic was 9.25 mm (P = less than .001).
"You could really tell a mother with [a] 9-month old baby based on IgE and skin test that [there is a] possibility of outgrowing" the allergy within 30 months. Both are "very useful predictors," Dr. Wood said.
In the eczema study, 27 (46%) of 59 infants aged 3-15 months with mild eczema resolved their milk allergies within 2 years, while only 41 (25%) of 165 with moderate to severe eczema outgrew their allergy (P = .004).
However, in a finding that may surprise some allergists, just 12 (19%) of 62 children enrolled with moderate to severe eczema outgrew their allergy even though their eczema improved to none or mild; among 66 children whose eczema didn’t improve, 21 (32%) outgrew their allergy (P = .11).
"We saw kids whose eczema got a lot better who stayed allergic, and other kids whose eczema stayed severe who managed to outgrow their allergies," Dr. Wood said.
That’s surprising because "there’s just sort of an assumption that many allergists [have] that as atopic dermatitis [gets better, children] are more likely to outgrow their food allergy. What this study showed was there wasn’t that direct line," he said.
Dr. Wood and his colleagues also looked at egg allergy; 13 (39%) of 33 children with no or mild eczema at enrollment outgrew their egg allergy within 2 years, compared with 19 (21%) of 89 enrolled with moderate to severe eczema (P = .047).
About a quarter resolved their egg allergies whether their eczema improved or not, but the finding wasn’t statistically significant.
Dr. Wood said he had no relevant financial disclosures.