Airway hyperresponsiveness to hypertonic saline as a predictive index of exercise-induced bronchoconstriction.
BACKGROUND
Changes in airway mucosal osmolarity are an underlying mechanism of bronchoconstrictive responses to exercise and hypertonic saline (HS). The purpose of this study was to examine whether an osmotic challenge test using HS can predict exercise-induced bronchospasm (EIB) in asthma patients.


METHODS
Thirty-six young male asthmatic patients underwent bronchial challenge tests based on 4.5% HS, exercise (> 24h later), and methacholine (MCh) at the Chonnam National University Hospital. The relationships between responses to HS and exercise, and between MCh and exercise were evaluated.


RESULTS
The maximal fall in forced expiratory volume in one second following exercise was significantly higher in the HS-responders (n=19) than in the HS-nonresponders (n=17, 35.9 +/- 4.1% vs. 17.9 +/- 2.7%, p<0.001), and there was a significant correlation between the severity of EIB and HS-airway hyperresponsiveness (AHR). When compared with the MCh-AHR test in terms of predicting EIB, the HS-AHR test showed higher specificity (71.4% vs. 42.90%), but a lower sensitivity (58.6% vs. 89.7%) and negative predictive value (29.4% vs. 50.0%). At the moderate AHR cutoff value, the MCh-AHR test had a specificity that was comparable with and predictive values that were higher than those of the HS-AHR test.


CONCLUSIONS
The HS-AHR test was more specific than the MCh-AHR test, but was less sensitive and had a poorer negative predictive value, which in combination preclude the use of the HS-AHR test as a screening tool for EIB. The MCh-AHR test had a cutoff value for moderate AHR that may be more useful for predicting EIB in asthmatic patients.
Department of Allergy, Chonnam National University Medical School and Chonnam National University Research Institute of Medical Sciences, Gwangju, Korea. ischoi@chonnam.chonnam.ac.kr
Inseon S
IS
Choi
Se-Woong
SW
Chung
Youngil I
YI
Koh
Myoung-Ki
MK
Sim
Seo-Na
SN
Hong
Jang-Sik
JS
Moon
D000293:Adolescent; D000328:Adult; D001250:Asthma, Exercise-Induced / Q000175:diagnosis*; D016535:Bronchial Hyperreactivity / Q000175:diagnosis*; D001985:Bronchial Provocation Tests / Q000379:methods*; D016085:Bronchoconstrictor Agents; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D011237:Predictive Value of Tests; D012462:Saline Solution, Hypertonic
D016085:Bronchoconstrictor Agents; D012462:Saline Solution, Hypertonic; D016210:Methacholine Chloride