Irreversible airway obstruction in asthma: A risk factor for severe exacerbations in spite of proper treatment

Abstract

Objectives: To evaluate whether irreversible airway obstruction (IAO) related to asthma is a risk factor for lack of symptoms control, poor quality of life and exacerbations. Methods: We evaluated consecutive outpatients with asthma in a one-year cohort study. We excluded subjects with smoke history > 9 pack-years. Definition of IAO was post bronchodilator FEV₁/CVF ratio below the lower limit of normality. Subjects received high dose of inhaled medications for asthma. We used logistic regression models, adjusted for the treatment offered during the study, to evaluate whether IAO related to asthma is a risk factor for symptoms control, quality of life, any emergency room visit, number of emergency room visits and hospital admission. Results: We enrolled 248 subjects in the study. IAO was not a risk factor for poor symptoms control [OR 1.354, 95 CI (0.632–2.899)] or worse asthma related quality of life [OR 0.705, 95 CI (0.413–1.204)]. Subjects with IAO had higher odds of any emergency room visit [OR 2.214, 95 CI (1.300–3.768)] and hospital admission [OR 8.530, 95 CI (1.517–47.978)] and lower odds to reduce emergency room visits in the course of the follow-up period [OR 0.452, 95 CI (0.265–0.769)]. IAO did not predict the number of emergency room visits [OR 1.53, 95 CI (0.71–3.30). Conclusion: IAO is not a risk factor for poor symptoms control or poor quality of life, in a setting of proper treatment. It is a risk factor for emergency room visit and hospital admission. Subjects with IAO have poor response to treatment.

Keywords:

• Control/management
• morbidity
• mortality
• pharmacotherapy
• quality of life
• treatment

Declaration of interest

All authors declare no conflict of interest and no financial relationships with companies that have an interest in the subject matter of this manuscript. The authors are responsible for the content and the writing of this article.

Funding

We acknowledge CNPq/FAPESB for financial support (Grant 020/2009 - PRONEX – 6353 – PNX0018/2009). Alvaro A. Cruz was awarded a grant to contitute Núcleo de Excelência em Asma, Universidade Federal da Bahia from CNPq/FAPESB (Edital 020/2009 - PRONEX – 6353 – PNX0018/2009).