Most mothers of food-allergic children who claim to have food sensitivities themselves do not meet clinical criteria for true allergies, a researcher reported here.
Barely 20% of the mothers who claimed to have food allergies had been diagnosed by a physician and had elevated food-specific IgE levels consistent with an allergy, according to Melanie M. Makhija, MD, of Children’s Memorial Hospital in Chicago.
The survey of 1,096 mothers of children with food allergies identified 221 who said they were allergic to certain food themselves, but only 117 said it had been confirmed by a physician, according to Makhija’s poster at the American Academy of Allergy, Asthma, and Immunology’s annual meeting.
And for most foods to which the mothers claimed to be allergic, most of the women had serum IgE levels greater than the cutoffs normally used for confirming a genuine allergy.
But Makhija suggested that the cutoffs may not adequately reflect allergy in adults, having been established mainly on the basis of pediatric data.
Parents of children with food allergies would likely be more alert to allergy symptoms in themselves, compared with adults lacking such experience, Makhija and colleagues reasoned.
Therefore they sought to establish correlations between self-reported allergies and those confirmed by physicians and IgE testing.
Women with at least one child under treatment for food allergy in Chicago were given the survey, which asked about food allergy symptoms and whether it had been diagnosed by a physician. The researchers relied on the self-report and did not check responses against medical records.
Mean age of respondents was 38. More than 80% were white and of moderate to high socioeconomic status. In addition to the approximately 20% who said they had food allergies, almost 60% reported suffering from allergic rhinitis, 25% said they had atopic dermatitis, and 24% indicated they had asthma.
Nine foods were assessed: Peanut, milk, egg, walnut, soy, wheat, shrimp, codfish, and sesame. In those who underwent IgE testing (about 70% of those saying they were allergic), the most common was shrimp, named by 47 respondents, followed by milk (28), peanut (27), codfish (17), soy (15), and wheat (13).
Women reporting peanut allergy were most likely to have it confirmed by physician diagnosis and serum IgE results, with a 44% confirmation rate.
The accuracy of the self-report fell off rapidly from there. One-third of mothers claiming a soy allergy had received a physician diagnosis and had high anti-soy IgE levels. For the other six foods, fewer than 20% of the reports were supported by physician diagnosis and IgE testing.
The least accurate claims were for milk and shrimp allergies. These allergies were confirmed in only one of the 28 with self-reported milk allergy and in just seven of the 47 who said shrimp was problematic.
Overall, of 147 mothers reporting food allergies and undergoing IgE testing, 30 had a physician diagnosis and high food-specific IgE.
Aside from the reliance on self-report of physician diagnosis, the study’s chief limitation was its use of 35 kU/L as the cutoff for IgE confirmation of allergy. Makhija and colleagues explained that this was the value given in the literature as providing 95% positive predictive value, but much of the underlying data were from pediatric studies.
Equally accurate cutoffs for adults could be different, they indicated.
The study was funded by the Food Allergy Project, the National Center for Research Resources, the Chicago Community Trust, the Sacks Family Fund, and the state of Illinois.
Authors said they had no relevant financial interests.
Primary source: American Academy of Allergy, Asthma, and Immunology
Source reference: Makhija M, et al “Mothers of food allergic children over-report food allergy in themselves” AAAAI 2012; Abstract 650.
By John Gever