title: A study of the association between exercise-induced wheeze and exercise versus methacholine-induced bronchoconstriction in adolescents.
abstract: Among asthmatics, exercise-induced wheeze (EIW) is a frequent symptom, and 40-77% of asthmatics demonstrate exercise-induced bronchoconstriction (EIB). In the North-Trøndelag population-based survey of 8,571 adolescents (YOUNG-HUNT), 26% reported wheeze during the previous 12 months (current wheeze). Of those subjects, 50% reported EIW. The aim of the present study was to investigate the association between EIW and EIB in randomly selected adolescents with EIW as the only or predominant asthma-like symptom, and to relate our findings to results from methacholine bronchoprovocation tests (MT) and measurements of exhaled nitric oxide (ENO). Sixty-three subjects with current wheeze induced by exercise, but not by allergen exposure, were investigated using a treadmill exercise test (ET) and measurements of ENO. Fifty-eight subjects completed a MT on a separate study day. EIB was defined as a fall of >or= 10% in the forced expiratory volume in 1 second (FEV1) after exercise (DeltaFEV1%ex). Twenty-one subjects (33%) had EIB and 33 (57%) had a positive MT. The degree of reported dyspnea during the ET was not correlated to the DeltaFEV1%ex. The correlation between EIB and methacholine-induced bronchoconstriction (MIB) was poor, and the DeltaFEV1%ex was more pronounced in smokers than in non-smokers. Moreover, ENO was not increased in subjects with positive vs. negative ET. Hence, EIW, when reported as the only or predominant asthma-like symptom, was linked to EIB in only one-third of the patients. We conclude that EIW is a poor predictor of EIB in epidemiological studies. The poor correlation between EIB and MIB indicates that these two tests measure different mechanisms of bronchial hyper-responsiveness.
authors.affiliation: Department of Lung Medicine, Norwegian University of Science and Technology, Trondheim, Norway. anne.h.henriksen@medisin.ntnu.no
authors.forename: Anne Hildur
authors.initials: AH
authors.lastname: Henriksen
authors.forename: Kjerst Hafstad
authors.initials: KH
authors.lastname: Tveit
authors.forename: Turid Lingaas
authors.initials: TL
authors.lastname: Holmen
authors.forename: Malcolm
authors.initials: M
authors.lastname: Sue-Chu
authors.forename: Leif
authors.initials: L
authors.lastname: Bjermer
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000175:diagnosis / Q000503:physiopathology*; D001250:Asthma, Exercise-Induced / Q000175:diagnosis / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D009569:Nitric Oxide / Q000378:metabolism; D012135:Respiratory Sounds / Q000175:diagnosis / Q000503:physiopathology*
chemical_list: D016210:Methacholine Chloride; D009569:Nitric Oxide