Children who participated in the intervention had 21 fewer days of symptoms than the control group in the first year and an average of 16 fewer days during the second, follow-up year.
"We wanted this to have a long-term impact, not just for the duration of the study," Dr. Gruchalla said. "In many cases, we taught them simple cleaning measures to decrease the roach population things like not leaving food uncovered and caulking obvious cracks in the wall."
Interventions also included encasing the child's mattress, springs and pillow in allergen-impermeable covers; repairing water leaks; and removing carpet from the bedroom, if possible. Families were also given HEPA (high efficiency particulate air) filters. Cockroach extermination visits were provided in homes where children were sensitive to that allergen. The suggestions were typically well-received, Dr. Gruchalla said.
Study participants had suffered at least one asthma-related hospitalization or two asthma-related unscheduled doctor visits the six months prior to enrollment in the study. They also had a positive allergy skin test to at least one of 11 indoor allergens such as dust mites, molds, cockroaches, pets or rodents.
Researchers performed a baseline clinical evaluation, including questionnaires on asthma symptoms, medication use and the home environment. Later, researchers made a baseline home evaluation by visually inspecting and collecting dust from the child's bedroom. The families were then taught how to reduce allergens in their homes, told why it was necessary and given the needed tools to accomplish the task. Researchers followed up by phone and collected information about the child's asthma every few months during the intervention year and one year after.