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May 12, 2006
Can Inhaled Corticosteroids Prevent Asthma?
Asthma, the most common chronic childhood illness in the United States, is a breathing disease in which the airways are inflamed, making breathing difficult. Studies in older children and adults show that inhaled corticosteroids are the most effective long-term control medicine for persistent asthma. These medicines reduce airway swelling and help prevent asthma symptoms. Pediatricians and researchers have wondered for years whether it can also be used to prevent the disease if it's given early enough. A new study supported by NIH's National Heart, Lung and Blood Institute (NHLBI) shows that, while they can reduce breathing problems in pre-school-aged children at high risk for asthma, inhaled corticosteroids don't prevent the development of persistent asthma.
Researchers have known that in most cases of chronic asthma, symptoms such as frequent coughing, wheezing or shortness of breath begin during the first 3 years of life. Declines in lung function can occur this early as well. However, few studies have been done in children less than 4 years old.
In the new study, 285 children ages 2-3 at high risk for asthma were randomly selected to receive either daily treatment of an inhaled corticosteroid — fluticasone propionate (Flovent) — or a placebo for 2 years. All children in the study received additional medication to treat any symptoms that arose. After 2 years, daily use of the inhaled corticosteroids (or placebo) was stopped, and the children were observed for an additional year to see if the earlier treatment had lasting effects.
In the May 11 issue of the New England Journal of Medicine, the researchers report no significant differences between the participants in the treatment group and those in the placebo group during the observation period. During the two-year treatment period itself, however, children treated with the daily inhaled corticosteroids had significantly fewer and less severe asthma symptoms than their peers who were given placebo.
Like an earlier report of older children, the study found that the inhaled corticosteroids appeared to temporarily slow the growth of children in the treatment group. The difference in growth was significant between the 2 groups during the first year of the study, but not during the second year — and during the third-year observation period, the children who had been regularly treated with inhaled corticosteroids grew more quickly.
Inhaled corticosteroids don't seem to prevent asthma from developing in children under 4 years of age. However, this study does show that inhaled corticosteroids can prevent asthma symptoms in pre-school children at high risk for asthma.