Exercise-induced asthma in children: a marker of airway inflammation.

What we know: Exercise-induced asthma (EIA) occurs in up to 23% of schoolchildren. In 40% of children with demonstrable EIA, no clinical diagnosis of asthma has been made. Children with asthma and EIA have eosinophils in their sputum, consistent with active asthma. EIA is well controlled in 50%-65% of children with moderate to severe asthma, so that only a minority will need prophylactic therapy immediately before exercise. Beta(2)-agonists are not the most suitable therapy for preventing EIA if they need to be used on a daily basis. The severity of EIA appears to be an indirect index of the severity of airway inflammation. What we need to know: Do non-symptomatic children with EIA require treatment for asthma? Does failure to identify and treat children unaware of their airways narrowing after exercise lead to airflow limitation in the long term, particularly in the small airways? Can exercise, or surrogate tests used to identify EIA, also be used to assess children with asthma? What is the minimum dose of steroid required to inhibit EIA, as high doses of steroids may be inappropriate in children? What is the best prophylactic treatment for EIA in children whose asthma is otherwise well controlled by inhaled steroids? What is the best prophylactic treatment for EIA in children with frequent episodic asthma or mild persistent asthma? Are leukotriene antagonists alone better than beta(2)-agonists alone in preventing EIA throughout the day? How many children taking long-acting beta(2)-agonists twice daily, either alone or in combination with an inhaled steroid, experience breakthrough EIA during school and require rescue medication?