Determinants of the severity of exercise-induced bronchoconstriction in patients with asthma.
OBJECTIVE
In examining the mechanisms of exercise-induced bronchoconstriction (EIB), it is important to determine which factors most strongly affect the severity of EIB. We determined such factors in patients with asthma by stepwise multiple-regression analysis.


METHODS
Twenty-three patients with asthma underwent pulmonary function tests, methacholine provocation test, and sputum induction. Eosinophilic inflammatory indices and airway vascular permeability index (ratio of albumin concentrations in induced sputum and serum) were examined in sputum samples, and then an exercise test was performed by all asthmatics.


RESULTS
There was a significant correlation between the severity of EIB and degree of eosinophilic inflammation in induced sputum. Moreover, there was a significant correlation between the severity of EIB and airway vascular permeability index. Although we could not find a significant correlation between the severity of EIB and 1-sec forced expired volume, 20% provocation concentration of (PC20) methacholine tended to be correlated with the severity of EIB. By stepwise multiple-regression analysis, we also found that airway vascular permeability index, eosinophil cationic protein levels in sputum, and PC20 methacholine are independent predictors of the severity of EIB.


CONCLUSIONS
We found that airway vascular hyperpermeability, eosinophilic inflammation, and bronchial hyperreactivity are independent factors predicting the severity of EIB.
Otani
Kenichiro
K
Department of Respiratory Medicine, Graduate School of Medicine, Osaka City University, Osaka, Japan. k-ootani@msic.med.osaka-cu.ac.jp
Kanazawa
Hiroshi
H
Fujiwara
Hiroshi
H
Hirata
Kazuto
K
Fujimoto
Shigeo
S
Yoshikawa
Junichi
J
D000328:Adult; D001249:Asthma / Q000276:immunology / Q000503:physiopathology; D001250:Asthma, Exercise-Induced / Q000276:immunology* / Q000503:physiopathology*; D001980:Bronchi / Q000503:physiopathology; D002199:Capillary Permeability / Q000502:physiology*; D004804:Eosinophils / Q000276:immunology*; D005260:Female; D006801:Humans; D008297:Male; D012129:Respiratory Function Tests; D012307:Risk Factors; D012720:Severity of Illness Index