Prevalence and characteristics of exercise-induced asthma in children

We have evaluated the prevalence and the characteristics of exercise-induce d asthma (EIA) in a group of 71 patients with a prior history of mild, mode rate or severe asthma (42 males and 29 females), aged 6-16 years-old. Measu rements of the forced expiratory volume in 1 second (FEV1) were obtained be fore and at regular intervals up to 8 hours following exercise. As a contro l, the same patients were evaluated at similar time intervals on another da y when they had not been submitted to an exercise challenge. Using pre-exer cise FEV1 values as the reference, 32 patients (45.1%) had a positive exerc ise challenge, defined as a fall in FEV1 value equal to or greater than 15% from baseline following exercise. Among the patients with a positive exerc ise challenge, the majority (23/32, 71.8%) had an immediate response alone, with no significant changes in FEV1 within the 8-hour follow-up. However, a subgroup of patients (9/32, 28.1%) had both an immediate and a late-phase response to exercise. During the control day, no significant fall in FEV1 were observed. In keeping with previous investigations, no correlation was found between a history of EIA and a positive exercise challenge in the pre sent study. Positive exercise challenges were found more frequently among p atients with moderate and severe asthma than patients with mild asthma.