Inner City Asthma Study: Relationships Among Sensitivity, Allergen Exposure, and Asthma Morbidity
Authors: Le Bras Michael , Jones Stacie M. 
Published: September 2006

Purpose of the Study.

To describe the relationship between allergen sensitivities, allergen exposures, and asthma morbidity in children with moderate-to-severe asthma while also exploring geographic variations in indoor allergen levels.

Study Population.

Subjects were children aged 5 to 11 years (n = 937) from 7 inner-city and metropolitan areas across the United States participating in the Inner City Asthma Study.

Methods.

In a fully crossed factorial design, participants were randomly assigned to receive an allergen intervention, bimonthly feedback of the child’s health status to their primary care physicians, both interventions, or no intervention (control group, n = 234). At baseline, a clinical interview with the child’s primary caregiver (including demographics, asthma morbidity, home characteristics, and exposure to tobacco smoke) was conducted with skin-prick tests to aeroallergens. Morbidity was measured at 2-month intervals during a 24-month period. Home visits including a visual inspection and dust-sample collection (dust mite, cockroach, cat and dog dander) were conducted at baseline and every 6 months.

Results.

Of 1059 children tested, 94% had at least 1 positive skin test. Allergen sensitivities varied widely across the study sites, with cockroach (69%), dust mites (62%), and molds (50%) being the most predominant. Cockroach sensitivity was highest in The Bronx, New York, New York City, New York, and Dallas, Texas (81%, 79%, and 79%, respectively), whereas dust mite sensitivities were highest in Dallas and Seattle, Washington (84% and 78%, respectively). At least 30% of the subjects were allergic to cats at all sites. Cockroach levels were highest (&gt;50% of homes) in Chicago, Illinois, New York City, The Bronx, and Dallas and were lower in Seattle and Tucson, Arizona (8% and 11% of homes, respectively). Dust mite levels were highest in Seattle and Dallas. Cockroach levels were higher in high-rise and low-rise apartments, whereas dust mite levels were higher in detached homes. No correlation was seen between animal dander and housing type.

Conclusions.

There were significant differences between geographic study sites and the type of indoor allergen exposure and skin-test sensitivity in this study group. Cockroach predominated in the Northeast, whereas dust mite predominated in the South and Northwest. Although most children in the study were allergic to dust mite and/or cockroaches, only the children who were sensitive and exposed to cockroach had increased asthma morbidity.

Reviewer Comments.

This study demonstrates the association of allergen sensitivities and exposures (particularly cockroach allergens) to increased asthma morbidity in children with moderate-to-severe asthma living in inner-city areas. Physicians can use this knowledge to identify significant risk factors in asthmatic patients, implement appropriate prevention measures (ie, environmental intervention), and more aggressive medical management to decrease the level of asthma morbidity.