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The importance of maximal airway response to methacholine in the prediction of wheezing development in patients with cough‐variant asthma
Author(s) -
Koh Y. Y.,
Park Y.,
Kim C. K.
Publication year - 2002
Publication title -
allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.363
H-Index - 173
eISSN - 1398-9995
pISSN - 0105-4538
DOI - 10.1034/j.1398-9995.2002.23602.x
Subject(s) - medicine , methacholine , asthma , airway , inhalation , anesthesia , chronic cough , respiratory disease , lung
Background: A significant proportion of patients diagnosed with cough‐variant asthma eventually manifest classic asthma signs, such as wheezing and dyspnea. The aim of this study was to investigate whether the degree of airway hypersensitivity and/or the level of maximal airway response can predict the development of wheezing in subjects with cough‐variant asthma. Methods: At study initiation, a high‐dose methacholine inhalation test was performed to measure provocative concentration causing a 20% fall (PC 20 ) in forced expiratory volume in 1 s (FEV 1 ) and maximal airway response. Each person was evaluated regularly every 3 months for 4 years and also on the occasion of wheezing being perceived for the first time. Results: Of the 48 patients available in the follow‐up period, 21 (Group 1) developed clinical wheezing, while 27 (Group 2) did not. There was no significant difference in PC 20 levels between the two groups. The level of maximal airway response, however, was significantly higher in Group 1 than in Group 2. The score test for trend revealed a significant association between the future development of wheezing and the level of maximal airway response ( P = 0.007), but not the level of methacholine PC 20 ( P = 0.423). Conclusions: The level of maximal airway response, rather than the degree of airway hypersensitivity, may be an important risk factor for the future development of classic asthma in patients with cough‐variant asthma.