Abstract
Background: Fixed airway obstruction in asthma, which could be also called as asthma-chronic obstructive pulmonary disease (COPD) overlap, is associated with more morbidity and mortality burden, particularly in the elderly. However, risk factors for developing fixed airway obstruction are still under studied in elderly asthma patients.
Objectives: We aimed to investigate risk factors of fixed airway obstruction among a group of elderly asthma patients.
Methods: A total of 306 patients were included. Their lung function parameters during 3-year treatment period were collected, and fixed airway obstruction was defined if the best FEV1/FVC was less than 0.70 during the recent 1-year's treatment period. Baseline parameters such as disease duration, smoking history, comorbidity, or serum IgE levels were analyzed for the associations with fixed airway obstruction.
Results: The prevalence of fixed airway obstruction was 40.2% in our group of elderly asthma patients (mean age 71.3 years old). In univariate analyses, fixed airway obstruction was significantly associated with older age, male sex, smoking history, lower body mass index, and serum staphylococcal enterotoxin-specific IgE (SE-IgE) levels. In multiple logistic regression analyses, smoking history had the strong association with fixed airway obstruction. However, SE-IgE levels also had the significant relationships with fixed airway obstruction, independently of smoking history.
Conclusions: Smoking history is a significant risk factor for fixed airway obstruction in elderly asthma. Our identification of SE-IgE sensitization as a potential risk factor for COPD overlap in elderly asthma warrants further investigation of its mechanism and clinical implication.
- Copyright ©the authors 2016