Clinical features predictive of exercise-induced asthma in children.

Exercise-induced asthma (EIA) is a common symptom among young asthmatics. The hypothesis that asymptomatic day-to-day wide fluctuations in lung function and asymptomatic persistent airflow obstruction are risk factors for the development of EIA was studied. The study population was a cohort of known asthmatic children aged 9-14 years attending a residential asthma camp. The method involved the observation of baseline expiratory peak flow recordings (PEFR) for 5 days while the children were receiving their usual maintenance therapy. The method also included the determination of FEV1 pre- and post- 15 min of continuous aerobic exercise. Exercise-induced asthma was expressed as the Lability index (LI). The findings were that LI was significantly correlated (P < 0.01) with the mean PEFR as a per cent of each child's predicted PEFR. The lability index also correlated (P < 0.01) with the degree of day-to-day variability in PEFR expressed as the coefficient of variance (CV). It is concluded that there is a significant correlation between baseline asthma control and the development of EIA. In addition to recommending pre-exercise prophylaxis, practitioners should investigate overall asthma control in children reporting EIA.