PREVALENCE OF EXERCISE-INDUCED AIRWAY NARROWING IN SCHOOLCHILDREN FROM A MEDITERRANEAN TOWN

A cross-sectional study was carried out on a random sample of 2,216 sc hoolchildren 9 to 14 yr of age to determine the prevalence of exercise -induced airway narrowing (EIAN) in a Mediterranean town (Mataro). A c omplementary case-control study measured the association between EIAN and respiratory symptoms. A free-running test was performed during sch ool time. Peak expiratory flow rate (PEFR) was measured at rest and at 2, 5, 10, and 15 min after exercise. A total of 136 of 2,056 satisfac tory runs showed a decrease of PEFR equal to or higher than 15% at eac h of these times after exercise. Five more children developed wheezing during running and were considered to have EIAN. Prevalence of EIAN w as 6.9% (95% Cl = 5.9 to 7.9). Prevalence decreased progressively with age. No sex difference was found. In the case-control study a questio nnaire of respiratory symptoms was applied to the mothers of hyperresp onsive children, as well as to two matched control subjects for each c ase. Questionnaire analysis showed a strong association between EIAN a nd respiratory symptoms or rhinitis. Association with bronchitis befor e 2 yr of age and parental asthma was less but significant.