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Factors associated with persistent airflow limitation in severe asthma
A ten Brinke1, A H Zwinderman, P J Sterk
1Department of Pulmonary Diseases, Leiden University Medical Center, Leiden University, Leiden, The Netherlands. a.ten_brinke@lumc.nl
American Journal of Respiratory and Critical Care Medicine
|September 11, 2001
Summary
Persistent airflow limitation is common in severe asthma patients, affecting nearly half of those studied. Sputum eosinophilia is a key independent risk factor, suggesting eosinophilic inflammation contributes to this condition.
Area of Science:
- Pulmonology
- Allergy and Immunology
- Respiratory Medicine
Background:
- Persistent airflow limitation can occur in non-smoking asthma patients.
- The prevalence and risk factors for incomplete reversibility in asthma-related airway obstruction are not well understood.
Purpose of the Study:
- To determine the prevalence of persistent airflow limitation in severe asthma patients.
- To identify clinical characteristics and inflammatory markers associated with persistent airflow limitation in this population.
Main Methods:
- Assessed 132 non-smoking severe asthma outpatients using standardized criteria for airflow limitation (postbronchodilator FEV(1) or FEV(1)/VC < 75% predicted).
- Analyzed associations with age at onset, asthma duration, atopic status, airway hyperresponsiveness (PC(20)histamine), and inflammatory markers (exhaled nitric oxide, blood eosinophils, sputum eosinophilia/neutrophilia).
- Utilized multiple logistic regression to calculate adjusted odds ratios (OR).
Main Results:
- Persistent airflow limitation was present in 49% of patients.
- Associated factors included older age, longer asthma duration, airway hyperresponsiveness (PC(20)histamine < 1.0 mg/ml; OR=3.9), and adult-onset asthma (OR=3.3).
- Sputum eosinophilia (≥2%) was independently associated with persistent airflow limitation (OR=8.9).
Conclusions:
- Persistent airflow limitation is prevalent in severe adult asthma.
- Adult onset, airway hyperresponsiveness, and particularly sputum eosinophilia are linked to persistent airflow limitation.
- Eosinophilic airway inflammation likely plays a role in the development of persistent airflow limitation in severe asthma.