Résumé
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. 42.9%), 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.
Sujets)
Mâle , Humains , Adulte , Adolescent , Solution saline hypertonique , Valeur prédictive des tests , Chlorure de méthacholine , Bronchoconstricteurs , Tests de provocation bronchique/méthodes , Hyperréactivité bronchique/diagnostic , Asthme à l'effort/diagnosticRésumé
BACKGROUND: Altered airway mucosal osmolarity is an underlying mechanism of bronchoconstrictive response to both exercise and hypertonic saline (HS). The purpose of this study was to examine whether the osmotic challenge test using HS could predict the exercise-induced bronchospasm (EIB) in asthma. METHODS: Thirty-six consecutive young male patients with asthma visited Chonnam National Univertisy Hospital underwent bronchial challenge tests using 4.5% HS, exercise (>24 hours later), and methacholine (MCh). The relationship in the responses between HS and exercise was observed in comparison with that between MCh and exercise. RESULTS: The maximal fall in forced expiratory volume in one second following exercise was significantly higher in the HS-responders (n=19) than that in the HS-nonresponders (n=17)(35.9 +/- 4.1% vs. 17.9 +/- 2.7%, p<0.001). There was a significant correlation between the severity of EIB and HS-airway hyperresponsiveness (AHR). Compared with the MCh-AHR test in diagnosing for EIB, the HS-AHR test showed a higher specificity (71.4% vs. 42.9%), but a lower sensitivity (58.6% vs. 89.7%) and a lower negative predictive value (29.4% vs. 50.0%). At the cutoff value for moderate AHR, the MCh-AHR test had specificity comparable with and predictive values higher than those of the HS-AHR test. CONCLUSION: The HS-AHR test was more specific than the MCh-AHR test, but less sensitive and had poor negative predictive value precluding from use of it as a screening test for EIB. The MCh-AHR test at the cutoff value for moderate AHR may be more useful in predicting EIB in asthma.