PURPOSE: We noted that some subjects with suspected asthma and a negative exercise challenge test (ECT) demonstrate improved expiratory flow rates following administration of bronchodilators (BD) at the end of the ECT. This study investigated whether this response predicts the presence of bronchial hyper reactivity (BHR).
METHODS: The study population included 133 young adults (29.4% women) aged 21.1± 4.2 years who underwent ECT and a methacholine challenge test (MCT). A receiver-operator-characteristic curve was employed 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 PC20 ≤; 4 mg/mL showed BHR in 12.8% of subjects. Failure to improve FEV1 by 8% following BD administration predicted the absence of BHR with sensitivity, specificity, positive and negative predictive values of 76.5%, 68.4%, 25.3% and 95.5%, respectively (Table 1). 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.
CONCLUSION: BD should be administered routinely following ECT, as the response may be used as a simple, inexpensive tool to predict BHR in young patients.
CLINICAL IMPLICATIONS: The response to BD should be documented routinely following negative ECT since it may substantially reduce the number of unnecessary MCTs.
DISCLOSURE: Oren Fruchter, No Financial Disclosure Information; No Product/Research Disclosure Information