system
Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, METHODS, RESULTS. Meshes: Asthma, Bronchial Provocation Tests, Bronchodilator Agents, Female, Follow-Up Studies, Forced Expiratory Volume, Humans, Male, Methacholine Chloride, Predictive Value of Tests, ROC Curve, Sensitivity and Specificity, Young Adult.
user
Does bronchodilator response after negative methacholine challenge test predict future diagnosis of asthma? Context: Currently there are no reliable means to predict the likelihood of a subject with negative results from a methacholine challenge test (MCT) to be diagnosed with asthma in the future. We sought to determine whether the magnitude of the response to bronchodilator (BD) administered after a negative MCT has a predictive value for future asthma. Over a 5 -year period, starting from January 2004, the change in the forced expiratory volume in 1 second (FEV(1)) after inhaling BD (salbutamol) was recorded among subjects with negative MCT despite symptoms suggestive of asthma such as wheezing and dyspnea. Subjects with a significant response to BD (defined as improvement in FEV(1) of more than 200 ml and 12%) were questioned for the presence of asthma on January 2009. Overall 645 subjects (mean age 21.4 +/- 2.3 years) underwent MCT. Negative MCT (defined as PC(20) > 16 mg/mL) was noted in 482 (74.7%) patients of whom significant response to BD was identified in 35. Over a median observation time of 2.1 years, 11 of them (31.4% of the study population and 1.7% of the entire cohort) were subsequently diagnosed with asthma. Improvement of FEV(1) by 20% predicted asthma with sensitivity, specificity, and positive predictive values of 86.9%, 66.6%, 83.3%, respectively, p = 0.0022.
assistant
Our findings suggest that administration of BD after a negative MCT enhances the diagnostic accuracy of the challenge test as it identifies subjects who are likely to develop clinical asthma in the future. Final Decision: yes