Exercise-induced respiratory symptoms are poor predictors of bronchoconstriction

Abstract

Exercise-induced asthma (EIA) is a possible cause of poor physical performance in children. No data are available on the value of respiratory symptoms to discriminate children with bad physical fitness from children with EIA. We evaluated respiratory symptoms in school-age children during and after exercise in relation to EIA. The population of 149 primary schools (849 classes with 15,241 children) was enrolled in the study. EIB was assessed using the 6-min free-running-test (6MFRT) in 15,241 children. At the end or at premature arrest of the 6MFRT, signs reported by the children and clinical symptoms observed by supervising physicians were recorded. Peak flow measurements were obtained before and 5 and 10 min after the 6MFRT, a decrease of 15% or more being defined as significant. The 6MFRT was positive in 7.4% of primary schoolchildren. Girls were more likely to have a positive test than boys (8.5% vs. 6.4%, P < 0.001), and children living in urban areas more than those living in rural areas (8.9% vs. 7.0%, P < 0.01). Premature arrest was seen in 3.5% (i.e., n = 353) of the children. The main reasons for premature arrest were dyspnea and chest pain. Among them, only 21% had a positive 6MFRT, while 89% with a positive 6MFRT could terminate the test. Premature arrest, breathlessness, chest tightness, wheezing, and cough had a positive predictive value to detect a EIA of 21.9%, 20.8%, 36.4%, 41.2%, and 28.3%, respectively, and a sensitivity of 10.8%, 29.5%, 14.9%, 4.8%, and 13.0%, respectively. In conclusion, EIA was detected in 7.4% of schoolchildren. A slightly higher incidence was observed in girls and children from an urban area. Neither premature arrest nor clinical signs and symptoms were good predictors of EIA in primary schoolchildren.