Response to bronchodilators after exercise challenge predicts bronchial hyperreactivity.
BACKGROUND
Some subjects with suspected asthma and a negative exercise challenge test (ECT) demonstrate improved expiratory flow rates after administration of bronchodilators (BD) at the end of the ECT (unpublished observation). This study investigated whether this response predicts the presence of bronchial hyperreactivity (BHR).


METHODS
The study population included 133 young adults (29.4% women) 21.1 +/- 4.2 years of age who underwent ECT and a methacholine challenge test (MCT). A receiver-operator-characteristic curve was used to calculate the optimal cutoff level of the response to BD as a predictor of BHR according to MCT.


RESULTS
Using a MCT cutoff level of PC(20) </= 4 mg/mL showed BHR in 12.8% of subjects. Failure to improve FEV(1) by 8% after BD administration predicted the absence of BHR with sensitivity, specificity, and positive and negative predictive values of 76.5%, 68.4%, 25.3%, and 95.5%, respectively. Avoiding MCT in subjects with less than 8% response to BD would have saved 62.5% of the MCTs and would have missed only four (3%) patients with BHR.


CONCLUSIONS
BD should be administered routinely after ECT, as the response may be used as a simple, inexpensive tool to predict BHR in young patients and may substantially reduce the number of unnecessary MCTs.
Division of Pulmonary Medicine, Rambam Health Care Campus, and Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
Oren
O
Fruchter
Mordechai
M
Yigla
D000293:Adolescent; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage*; D001499:Bayes Theorem; D016535:Bronchial Hyperreactivity / Q000175:diagnosis* / Q000453:epidemiology; D001985:Bronchial Provocation Tests; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D015331:Cohort Studies; D005080:Exercise Test / Q000379:methods*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D015994:Incidence; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D011237:Predictive Value of Tests; D011336:Probability; D012372:ROC Curve; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013147:Spirometry
D001993:Bronchodilator Agents; D016210:Methacholine Chloride; D000420:Albuterol