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A new study found specific factors that may contribute to a positive methacholine challenge test in patients with asthma.
Asthma is a common chronic inflammatory disease of the airways, characterized by obstruction of airflow to the lungs and bronchospasms, which are sudden muscle contractions of the walls of the bronchioles.
One of the ways to diagnose asthma is the methacholine challenge. In this case, the patient breathes in methacholine, which is a drug that causes airway constriction, specifically in those with a predisposition to asthmatic symptoms.
To determine the degree and factors that contribute to airway closure in response to methacholine, Kaminsky and colleagues investigated the administration of methacholine in patients that participated in five studies conducted by the American Lung Association-Airways Clinical Research Centers (ALA-ACRC). The study was published in Respirology.
They found that methacholine more likely caused airway closure in not only those with asthma but those that were older and obese. Since airway closure is an important feature of asthma, this needs to be addressed when providing treatment to patients, specifically the elderly and the obese.
Although this is the largest population investigated to date, about 936 patients, the study did contain some limitations. The main limitation was that the study was a retrospective, cross-sectional analysis. This means there may have been some variability between studies that were left unacknowledged which may have affected the overall results.
Read about the 10 things you may not know about asthma here.
Written by Unaisa Bhayat, BMedSc
Reference: Kaminsky D. A., Chapman D. G., Holbrook J. T., Henderson R. J., Sugar E. A., Mastronarde J., Teague W. G., Busk M., Sumino K., Dixon A. E., Wise R. A., Irvin C. G. Older age and obesity are associated with increased airway closure in response to methacholine in patients with asthma. Respirology. 2019.