Asthma symptoms, direct and indirect challenge tests in adolescent elite swimmers

Abstract

Background: The risk of developing asthma is increased in swimming most pronounced on the elite level. The aim of the study was to investigate the prevalence of asthma symptoms in adolescent elite swimmers and to compare these results by four different provocation tests. Methods: 101 swimmers answered a questionnaire about respiratory symptoms. Atopy was assessed by skin prick test, and fractional exhaled Nitric Oxide (FeNO) was measured. Mannitol provocation and sport specific exercise test were performed. Thirty-four of the swimmers from two swimming clubs (49%) performed isocapnic hyperventilation (ICHV) and metacholine provocation. Results: Asthma symptoms were common among the swimmers (62%). Metacholine provocation has the highest frequency of positive test results (61%), followed by mannitol provocation 15 (44%), ICHV 11 (32%) and sport-specific exercise test 9 (26%) positive tests. Ten of the swimmers (29%) had no positive provocation test. Two of the swimmers (6%) were positive in all four tests and eleven of the swimmers (32%) were positive in at least three of the four tests. The greatest overlap was between metacholine and mannitol provocation where 13 (39%) of the swimmers had positive results in both tests. Five swimmers (15%) did not report any asthma symptoms even if they had positive tests. Four swimmers (12%) reported asthma symptoms with no positive tests. Conclusion: The swimmers had a high prevalence of asthma symptoms and a high frequency of positive provocation tests. The mannitol provocation test seems to have a high sensitivity with few false positive tests. To get a correct diagnose you have to use more than one test even if there is a great overlap between the tests.