Severe exacerbations and irreversible airflow limitation in asthma

Published Online: June 5, 2015

A subset of asthma patients is known to have rapid loss of lung function despite steroid therapy. There is a great need to define targets for attenuation of the progression of airway obstruction. Severe exacerbations of asthma are periods of excess functional and pathological changes in the airways that have been proposed to induce airway remodeling. A reduced bronchodilator response has been used as a surrogate marker for airway remodeling. However, no prospective study has examined whether severe asthma exacerbations are correlated with the decline in post-bronchodilator forced expiratory volume in 1 second (FEV1) and loss of bronchodilator reversibility (BDR).

In a study recently published in The Journal of Allergy and Clinical Immunology: In Practice, Matsunaga and colleagues explored the changes in FEV1 and BDR in 140 non-smoking patients with well-controlled asthma at baseline and correlated these changes with the frequency of severe asthma exacerbations over a 3-year period. This study demonstrated that the rate of severe asthma exacerbations is correlated with a more rapid decline in FEV1 and loss of BDR, and that there is a significant correlation between the rates of decline in FEV1 and the reductions in BDR that occurred over time. The causality between the asthma exacerbations and loss of lung function is still uncertain. Alternatively, it may be the severity of asthma and/or other patient factors such as asthma treatment and smoking history account for both the exacerbations and the lung function decline. However, the data presented by Matsunaga et al support the hypothesis that asthma exacerbations, representing intermittent periods of intense airway inflammation and excess bronchoconstriction, have a potential role in the progression of airway structural and functional changes leading to irreversible airflow limitation. This suggests that the prevention of asthma exacerbations could have a pivotal role in the attenuation of the long-term adverse consequences of structural and functional changes in the airways.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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