Asthma patients often undergo tests involving inhaled methacholine, a drug that can cause narrowing of the airways, similar to what occurs in asthma. In a Respirology analysis of data on patients undergoing such tests, obesity and older age were linked with higher risks of airway closure.

The analysis included 936 patients with asthma, among whom the median closing index was 0.67 relative to that of a published healthy population of 0.54. A higher closing index was associated with increased age and obesity. Therapies directed at airway closure may be important in patients with a high closing index.

“The results of this study confirm in the largest population to date that airway closure is an important feature of asthma pathophysiology, particularly in obese and older individuals, and therefore emphasize the importance of addressing airway closure in patients with asthma,” said lead author Dr. David Kaminsky, of the University of Vermont Larner College of Medicine.