Prevalence and characteristics of small airways disease in a general population

<bold>Rationale</bold>. Small airways disease (SAD) is being regarded as a precursor of chronic airway obstruction, such as in COPD and asthma. In clinical settings, SAD is commonly inferred from spirometry. The aims of this study were to estimate the prevalence of isolated SAD and describe its demographic and clinical characteristics in a large sample of the Austrian general population. <bold>Methods</bold>. This study is based on data from 6,906 adults (≥18 years) from the Austrian LEAD study. Isolated SAD was defined using spirometry as the ratio between the forced expiratory flow between 25% and 75% of vital capacity and forced vital capacity below the lower limit of normal (FEF25-75/FVC<LLN) with a normal ratio of the forced expiratory volume in the first one second to the FVC equal or above LLN (FEV1/FVC≥LLN). <bold>Results</bold>. Prevalence of spirometric isolated SAD was 6.7% (n=465) with no sex predominance (male 50.3% vs female 49.7%). People with isolated SAD were older (63.8 vs 51.4 years) and more likely to be current or former smokers (63.0% vs 49.0%) with a median of 6 pack-years. A higher proportion lived in a rural area (23.8% vs 20.0%) and had a lower education level (30.7% vs 26.2%). Respiratory symptoms including breathlessness, wheezing, phlegm, and cough (37.8% vs. 25.1%), chronic cough (8.9% vs. 4.9%), as well as self-reported doctor diagnosis of asthma (12.3% vs. 7.7%), were more common among people with isolated SAD. <bold>Conclusion</bold>. Our findings show that isolated SAD is common in the Austrian general population and provide valuable insights into its demographic and clinical characteristics.