METHODS: 350 mouse-sensitized and exposed asthmatic children (5-17y) were enrolled in a clinical trial of integrated pest management+education versus education alone. Symptoms and mouse allergen exposure were assessed every three months. Allergen reduction was defined as ≥75% reduction in bedroom mouse allergen. Groups were combined for analyses because there were no differences in exposure or clinical outcomes. Analyses of relationships between allergen reduction and symptoms were stratified by atopy (highly vs. less atopic (≥6 vs. <6 +SPTs)). Regression models were adjusted for gender, age, race, insurance, and included interaction terms (atopy*allergen reduction).
RESULTS: The participants were inner-city, low-income, asthmatics with poor control. 55% were highly atopic and 60% had ≥75% allergen reduction at ≥1 visit. Among less atopic participants, allergen reduction was associated with significantly (p<0.05) fewer symptom-days (OR [95% CI]: cough, wheeze, chest tightness: 0.63 [0.46-0.86], nocturnal: 0.49 [0.33-0.72], difficulty speaking: 0.25 [0.12-0.51], rescue medication: 0.58 [0.41-0.81]). There was little effect of allergen reduction on symptoms among highly atopic participants as all OR ≥0.91 and p>0.05. P-values for atopy-allergen reduction interactions were: cough, wheeze, chest tightness: 0.06, nocturnal symptoms: 0.02, difficulty speaking: 0.003, rescue medication: 0.05.
CONCLUSIONS: Mouse allergen reduction was associated with greater benefit among less atopic mouse-sensitized and exposed asthmatic children, suggesting that the effectiveness of allergen reduction interventions may vary by allergic phenotype.