Clinical characteristics of and risk factors for small airway dysfunction detected by impulse oscillometry

Background: Small airway dysfunction (SAD) is an early lesion of chronic respiratory disease that is best detected using impulse oscillometry (IOS). Few studies have investigated risk factors for IOS-defined SAD (IOS-SAD) in a large population. We aimed to explore the clinical features of and risk factors for IOS-SAD in a community-based population. Methods: We divided subjects into IOS-SAD and non-SAD groups based on a cutoff of >0.07 kPa/L/s in the difference between the resistance at 5 Hz versus the resistance at 20 Hz (R5-R20). All participants underwent spirometry, IOS, and completed a questionnaire; some participants underwent computed tomography (CT). We analyzed the risk factors for SAD based on binary logistic regression. Results: The total cohort comprised 1327 subjects. The prevalence of IOS-SAD was 32.9% (437/1327). Compared with the non-SAD group, the IOS-SAD group was older (64.0 +/- 7.8 vs. 59.6 +/- 7.8 years, p < 0.001), included less never-smokers (30.2% vs. 35.8%, p < 0.001), had greater airway resistance and worse lung function, indicated by a larger R5-R20 (0.15 +/- 0.08 vs. 0.03 +/- 0.02 kPa/L/s, p < 0.001) and smaller forced expiratory volume in 1 s to forced vital capacity after bronchodilation (60.2 +/- 14.4% vs. 72.6 +/- 10.0%, p < 0.001); on CT, the IOS-SAD group had higher prevalences of emphysema and gas trapping. Risk factors for SAD were older age, high BMI, smoking, childhood cough, and asthma. Conclusion: Subjects with IOS-SAD had increased airway resistance and visible CT changes. Individuals with smoking exposure, advanced age, high BMI, childhood cough, and asthma were more prone to SAD.

Automated summary

In a study of 1327 subjects, the prevalence of IOS-SAD in a community-based population was 32.9%, with the IOS-SAD group exhibiting increased airway resistance and poorer lung function compared to the non-SAD group. Risk factors for SAD included older age, higher BMI, smoking, childhood cough, and asthma.