PURPOSE OF THE STUDY.
These researchers sought to understand the relationship between allergen-specific immunoglobulin E (IgE) levels, exposure to indoor allergens, and asthma severity.
There were 546 subjects, aged 12 to 20 years, with physician-diagnosed moderate-to-severe asthma enrolled at 10 centers around the United States as part of the Asthma Control Evaluation (ACE) study.
Subjects underwent a 3-week run-in period in which asthma symptoms, medication use, pulmonary-function testing, and adherence data were collected. Skin testing was performed to a panel of 14 aeroallergens, and allergen-specific IgE levels to common indoor allergens were measured. A home visit was conducted to collect dust samples from the bed and bedroom floor. Subjects were then assigned to either a pharmacotherapy titrated according to National Asthma Education and Prevention Program (NAEPP) guidelines or pharmacotherapy titrated according to NAEPP guidelines and fractional exhaled nitric oxide (FeNO). Subjects were followed for 1 year, and data on exacerbations, health care utilization, and pulmonary function were collected at each visit.
Black subjects comprised 65% of the participants; 48% had an annual household income of less than $15 000. The majority (88%) were skin-test–positive to at least 1 aeroallergen including cockroach (61%), cat (58%), mold (52%), and dust mite (47%). There were statistically significant correlations between allergen-specific IgE levels and settled dust allergen concentrations for dust mite, cockroach, and mouse. Those with higher allergen-specific IgE levels to cockroach, mouse, cat, and dust mite had higher FeNO concentrations and peripheral blood eosinophils. Higher allergen-specific IgE levels were associated with lower lung function for all allergens, although not all were statistically significant.
In atopic asthmatic adolescents from the inner city, allergen-specific IgE levels were positively correlated with bedroom allergen exposure for dust mite, cockroach, and mouse allergens. Higher allergen-specific IgE levels were also associated with worse clinical and biomarker outcomes.
Indoor allergen burden has been proposed to be the reason for the increased asthma morbidity in inner-city populations. There have also been many attempts to find specific biomarkers that might better predict disease severity in asthma. These results indicate that for most indoor allergens, allergen-specific IgE levels might be a marker of allergen exposure and disease burden.
- Copyright © 2011 by the American Academy of Pediatrics