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Smoking, longer disease duration and absence of rhinosinusitis are related to fixed airway obstruction in Koreans with severe asthma: findings from the COREA study

Taehoon Lee1, Yoon Su Lee1, Yun-Jeong Bae1, Tae-Bum Kim1, Seon Ok Kim2, Sang-Heon Cho3, Hee-Bom Moon1, COhort for Reality and Evolution of adult Asthma in Korea study group (COREA study group)1 and You Sook Cho1*

Author Affiliations

1 Department of Allergy and Clinical Immunology, Asan Medical Center, University of Ulsan College of Medicine, Asanbyeongwon-gil 86, Songpa-gu, Seoul, 138-736, Korea

2 Department of Biostatistics, Asan Medical Center, University of Ulsan College of Medicine, Asanbyeongwon-gil 86, Songpa-gu, Seoul, 138-736, Korea

3 Department of Asthma, Allergy and Clinical Immunology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, 110-744, Korea

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Respiratory Research 2011, 12:1  doi:10.1186/1465-9921-12-1

Published: 3 January 2011



The clinical manifestations of severe asthma are heterogeneous. Some individuals with severe asthma develop irreversible fixed airway obstruction, which is associated with poor outcomes. We therefore investigated the factors associated with fixed airway obstruction in Korean patients with severe asthma.


Severe asthma patients from a Korean adult asthma cohort were divided into two groups according to the results of serial pulmonary function tests. One group had fixed airway obstruction (FAO) [forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) ratio < 0.7, n = 119] and the other had reversible airway obstruction (RAO) [FEV1/FVC ratio ≥ 0.7, n = 116]. Clinical and demographic parameters were compared between the two groups.


Multivariate analysis showed that longer duration of disease, greater amount of cigarette smoking and absence of rhinosinusitis were significantly related to the development of FAO in severe asthmatics. Other parameters, including atopic status, pattern of airway inflammatory cells in induced sputum, and frequency of asthma exacerbations did not differ between the FAO and RAO groups.


Severe asthma patients with longer disease duration and the absence of rhinosinusitis are more likely to develop FAO. This study also demonstrates the importance of quitting smoking in order to prevent irreversible airway obstruction. Further investigation is required to determine the mechanism by which these factors can modify the disease course in Korean patients with severe asthma.