Asthma Exacerbations Associated with Lung Function Decline in Patients with Severe Eosinophilic Asthma

Background: Limited data describe the association between the frequency of asthma exacerbations and the decline in lung function in severe asthma. Objective: To determine whether asthma exacerbations are associated with enhanced decline in lung function. Methods: Changes in lung function were analyzed retrospectively using data from the DREAM and MENSA studies of mepolizumab intervention in patients with severe asthma. Patients were either nonsmokers or former smokers. A linear regression model was used to analyze the relationship between the number of exacerbations and decline in FEV1 across treatment groups. Results: In a combined post hoc analysis, 57% (n = 572) of patients had no exacerbations and experienced an improvement in postbronchodilator FEV1 of 143 mL. In contrast, in patients who experienced 3 or more exacerbations, there was a decrease in postbronchodilator FEV1 of 77 mL in the combined analysis. The linear modeling analysis estimated that for each exacerbation seen during the observational period, there was a decrease of 50 mL in FEV1 (P < .001). Conclusions: A direct relationship between the number of exacerbations in patients with severe eosinophilic asthma and decline in lung function was observed. Repeated exacerbations may be associated with accelerated loss of lung function.