Pharmacological interventions. Childhood asthma.

Airway inflammation is present in early asthma. Chronic inflammation seems to be associated with airway remodelling and reduced growth of lung function. An inverse relationship between lung function and duration of asthma or an increase in bronchial reactivity with asthma duration has been reported in many studies. Several trials have found that late use of inhaled corticosteroids is associated with a smaller effect on bronchial hyperreactivity and lung function compared with early use. Furthermore, it has been suggested that early anti-inflammatory treatment may also influence long-term outcome. These findings have elicited the hope that it might be possible to cause disease resolution or modify the natural course of the disease. It has been hypothesized that there may be a window of opportunity in relation to the treatment of asthma after which remodelling and changes in lung function occur which cannot be reversed. However, just when this window of opportunity presents in the progression of the disease, or at what stage early intervention should be initiated, has not been clearly defined. Early pharmacological intervention in children <3 yrs of age is complicated by the fact that treatment will be given to a large number of children who will never develop persistent asthma. This must be considered when designing the studies addressing the various research questions about early pharmacological intervention. Studies in young children should probably be conducted in both high- and low-risk patients. Older patients with apparently mild disease are the main candidates for placebo-controlled trials. Patients with a greater disease severity are more suitable for studies comparing intervention with different drugs or different doses of drug.