Household mouse allergen exposure and asthma morbidity in inner-city preschool children

Background: Inner-city children experience disproportionate asthma morbidity, and suspected reasons include indoor environmental exposures. Objective: To determine if mouse allergen exposure is a risk factor for asthma morbidity. Methods: Preschool children with asthma were recruited from inner-city Baltimore, MD. Skin testing was performed and blood was collected at the baseline visit for quantification of mouse allergen specific IgE. A questionnaire evaluated symptoms, medication, and health care use at baseline, 3 months, and 6 months. A trained technician collected dust samples from the child's home for analysis of Mus m 1 at baseline, 3 months, and 6 months. Outcomes were compared between mouse-sensitized, highly exposed children and all other children. Results: A total of 127 children had complete data for mouse sensitization status and bedroom settled dust mouse allergen levels at baseline. The mean age of the children was 4.4 years, 92% were African American, and 26% were sensitized to mouse. Mouse-sensitized children exposed to higher levels of Mus in 1 (> 0.5 mu g/g) had 50% more days of symptoms (incidence rate ratio [IRR], 1.5; 95% confidence interval [CI], 1.1-2.1) and 80% more days of beta-agonist use than other children (IRR, 1.8; 95% CI, 1.3-2.5). Children in the sensitized and highly exposed group were also more likely to have an unscheduled physician visit (odds ratio [OR], 3.1; 95% CI, 1.6-6.3), emergency department visit (OR, 2.1; 95% CI, 1.1-4.1), and hospitalization (OR, 36.6; 95% CI, 4.1-327.3) than other children. These associations between mouse allergen exposure and asthma symptoms and morbidity remained statistically significant after adjusting for potential confounders, including atopy and cockroach sensitization and exposure. Conclusions: In mouse-sensitized inner-city children, exposure to mouse allergen may be an important cause of asthma morbidity.