Food Allergen Sensitization in Inner-City Children With Asthma
Authors: Burks Kelly D. , Jones Stacie M. 
Published: September 2006

Purpose of the Study.
To determine the prevalence of food allergen sensitization and its association with asthma symptoms and health care utilization in an inner-city asthma population.

Study Population.
Random serum samples were obtained from children (n = 544) aged 4 to 9 years (median: 6 years) with asthma living in inner-city areas enrolled in the National Cooperative Inner City-Asthma Study.

Methods.
Information regarding demographics, health history, medication use, health care utilization, and asthma symptoms was recorded on the basis of 3-month recall at baseline and at 3-month intervals for a period of 12 months. No information regarding food allergy diagnoses or reactions was obtained. Skin-prick testing to 13 environmental allergens was performed at enrollment in the National Cooperative Inner City-Asthma Study. The random serum samples were evaluated for specific immunoglobulin E (IgE) (UniCap System) to egg, milk, soy, peanut, wheat, and fish. On the basis of IgE levels, subjects were stratified into 4 groups: group 1, food-specific IgE levels that had &gt;95% positive predictive value for food allergy; group 2, probable food allergy (IgE ≥ 0.7 kU/L); group 3, any sensitization (IgE ≥ 0.35 kU/L); and group 4, no evidence of food allergy (IgE &lt; 0.35 kU/L).

Results.
There was a significant correlation between sensitization to foods and sensitization to aeroallergens, with sensitization to the highest number of aeroallergens correlating with sensitization to soy, wheat, and peanut. Forty-five percent of study patients were sensitized to at least one food (groups 1–3): 4% of the participants were categorized to group 1, 26% to group 2, and 14% to group 3. Fifty-five percent were not sensitized to any of the 6 foods (group 4). Food allergy to egg and peanut were associated with the highest specific IgE levels. Patients who were sensitized to at least one food had higher rates of hospitalization and steroid medication use. The food-sensitized groups required more medications in general, but this difference was not significant. Most group 1 children (96%) demonstrated sensitization to &gt;1 food, with 25% of the patients sensitized to all 6 foods tested. Most group 2 patients (75%) and 19% of group 3 patients were sensitized to multiple foods. There was a significant increase in hospitalizations for asthma in children sensitized to &gt;1 food. When specific foods were examined, a correlation between higher asthma morbidity and sensitization to fish or soy was noted.

Conclusions.
Food sensitization correlated with increased asthma severity in the study population. The prevalence of food allergy was not determined because of the nature of the study (anonymous serum samples and lack of blinded food challenges); however, on the basis of the study results, the authors predicted that inner-city children with asthma were more likely than the general population to have food allergy. The association of increased asthma morbidity with at least 1 food sensitization, and findings that patients with sensitization to multiple foods had significantly more asthma morbidity than those with single-food sensitization, suggest that food sensitization is a marker for increased asthma severity.

Reviewer Comments.
This study suggests that the prevalence of food sensitization, and possibly food allergy, is increased in patients with asthma and may be a useful marker for increased asthma severity. Health care providers should consider screening for food sensitization in patients with severe or poorly controlled asthma.