PT  - JOURNAL ARTICLE
AU  - Kazuto Matsunaga
AU  - Keiichiro Akamatsu
AU  - Masakazu Ichinose
TI  - Developing obstructive change over time is dominant in small airways in severe asthma
DP  - 2012 Sep 01
TA  - European Respiratory Journal
PG  - 342
VI  - 40
IP  - Suppl 56
4099  - http://erj.ersjournals.com/content/40/Suppl_56/342.short
4100  - http://erj.ersjournals.com/content/40/Suppl_56/342.full
SO  - Eur Respir J2012 Sep 01; 40
AB  - Background: The clinical features, physiology, and pathology of severe asthma are poorly understood. Recently, the forced vital capacity (FVC) has been shown to be reduced in severe asthma compared to mild asthma, possibly due to air trapping. However, the natural history of airway obstructive change for such asthmatic patients has not been fully elucidated. Objective: To assess the pattern and risk factors of developing airway obstruction over time in severe asthma. Methods: We examined the data of a retrospective analysis of lung function changes over a 10-year period in 54 patients with severe asthma. The risk factors that might contribute to the progression of obstructive changes were also investigated. Results: The rate of change in both FVC and FEV1 (forced expiratory volume in one second) was highly variable among the patients with severe asthma. The faster obstructive changes detected by decline in FEV1 were accompanied by excessive loss of FVC (r = 0.85, p < 0.0001) and the reduction in FVC was 1.2 times larger than the FEV1 decline. Age, baseline FVC, annual exacerbation rate and use of oral corticosteroids showed significantly negative correlations with the rate of annual change in FVC. Conclusions: These data indicate that the decline in FVC is more evident than FEV1 in severe asthma, suggesting that small airway susceptibility may be the cause of rapid disease progression. Aging, exacerbations of asthma, and use of systemic corticosteroids are associated with excess FVC decline, particularly if FVC is still normal.