Purpose of the Study
The “atopic march” is the common progression of allergic disorders in children from atopic dermatitis to allergic asthma. The aim of the study was to determine whether an 18-month course of cetirizine, an antihistamine with several antiallergic properties, could prevent the development of airway inflammation and asthma in infants with atopic dermatitis.
Over a 2-year period, 817 infants <2.5 years of age with atopic dermatitis, no history of wheezing, and at least one parent or sibling with a history of atopic disease were included in the ETAC (Early Treatment of the Atopic Child) trial, a multicountry, double-blind, randomized, placebo-controlled trial. Total and specific immunoglobulin E (IgE) [grass pollen, cow milk, egg, dust mite, and cat dander] were determined at entry, and after 3, 12, and 18 months. Infants were treated for 18 months with either cetirizine (0.25 mg/kg bid) or placebo, and the number of infants developing asthma was compared between the two groups.
Overall, there was no difference between the cetirizine- and placebo-treated groups in the number of infants developing asthma. However, in patients with increased total IgE (≥30 kU/l) or specific IgE (≥0.35 kUA/l) for grass pollen, dust mite, or cat dander, the relative risk (RR) for developing asthma was elevated (RR between 1.4 and 1.7). Compared with placebo, cetirizine significantly reduced the incidence of asthma for patients sensitized to grass pollen (RR = 0.5) or to house dust mite (RR = 0.6). The adverse events profile was similar in the two treatment groups.
In infants with atopic dermatitis, elevated levels of total IgE or specific IgE to grass pollen, house dust mite, or cat dander were predictive of subsequent asthma. In this “high-risk” group, cetirizine halved the number of children developing asthma after 18 months of treatment. In view of the proven safety of the drug, the authors propose treating such “high risk” infants with cetirizine to prevent the development of asthma.
These preliminary findings of the ETAC group are obviously of great interest and worth tracking. The follow-up period is too short to conclude that this pharmacologic intervention is going to be successful in preventing asthma, but it does raise the exciting possibility that we may be able to do something other than watch 50% to 60% of infants with atopic dermatitis progress on to asthma. The mechanism of this apparent prophylactic effect remains to be elucidated, and it is possible that other antihistamines, eg, loratidine and ketotifen, may be even more effective. Stay tuned.