Methacholine challenge testing is superior to the exercise challenge for detecting asthma in children

Background: Exercise-induced bronchoconstriction occurs in a large proportion of children with asthma. Objective: To compare the predictive value of methacholine challenge testing (MCCT) and the exercise treadmill challenge (ETC) for detecting asthma in children with postexercise symptoms. Methods: This was a prospective study of children 10 to 18 years old with postexercise symptoms. During asthma diagnosis, they underwent MCCT and ETC. There were 2 study visits. All subjects underwent ECT at visit 1 and MCCT 1 week later at visit 2. Results: One hundred one children were included; 62.9% had a history of atopy, and asthma was confirmed in 43.6%. MCCT showed 90.9% sensitivity, 82.5% specificity, 80.0% positive predictive value, and 92.2% negative predictive value; the respective values for ECT were 77.3%, 68.4%, 65.4%, and 79.6%. Positive MCCT results showed significantly higher sensitivity and higher positive predicative value in the diagnosis of asthma in children with postexercise symptoms compared with a 10% decrease in forced expiratory volume in 1 second for ECT (P = 0.034). Conducting MCCT during asthma diagnosis confirmed asthma in an additional 24.3% of children with exercise-induced symptoms. With a cutoff level at 17% of forced expiratory volume in 1 second for ECT, the discrepancy was decreased and reasonable values for sensitivity, specificity, positive predictive value, and negative predictive value were attained (61.0%, 77.1%, 69.4%, and 69.8%, respectively). Conclusion: A large number of school children with asthma and postexercise symptoms could have positive MCCT and negative ECT findings. Untreated asthma in children with exercise-induced bronchoconstriction could cause them to be discharged from physical education classes. (C) 2015 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.