A randomized controlled trial of allergen trigger reduction strategies to improve pediatric asthma outcomes

Background: Asthma is a serious, complex, and highly prevalent childhood disorder. In the U.S., pronounced disparities exist with the highest disease burden borne by low-income, minority children living in urban environments. Disparities are due, in large part, to greater exposure to asthma triggering allergens in the home. Guidelines based care recommends interventions targeting all allergens to which children are sensitized. However, it is unclear whether this is the most effective allergen reduction strategy. Numerous studies of inner-city cohorts have found that exposure to cockroaches may be driving disparities in asthma outcomes in inner city residents. The impact of reducing cockroaches on clinical outcomes is not known.

Methods: One hundred and two children ages 5-17 years with moderate to severe asthma were enrolled in a 12-month randomized controlled trial testing the use of insecticidal bait on cockroach counts and asthma morbidity. Homes were visited six times and asthma outcomes were assessed every 2 months.
For binary outcomes a logistic regression model was applied. For continuous outcomes, a semi-parametric model was applied.

Results: After adjustment, intervention homes had significantly fewer cockroaches than control homes (mean change in cockroaches trapped 13.14, 95% CI: 6.88, 19.39, p < 0.01). Children in control homes had more asthma symptoms and unscheduled healthcare utilization in the previous 2 weeks (1.82, 95% CI: 0.14, 3.50, p = 0.03; 1.17, 95% CI: 0.11, 2.24, p = 0.03, respectively) and a higher proportion of children with FEV1 < 80% predicted (OR 5.74, 95% CI: 1.60, 20.57, p = 0.01) compared to children living in homes receiving the cockroach abatement intervention.

Conclusions: Clinical guidelines recommend a multi-component approach to allergen trigger reduction in the home. We found that the strategic placement of insecticidal bait which is inexpensive, has low toxicity, and is widely available, resulted in sustained cockroach elimination over 12 months and was associated with improve asthma outcomes. This single intervention may be an alternative to multifaceted interventions currently recommended to improve asthma morbidity in households with cockroach exposure.