Small airways disease is a pathological feature in mild to moderate COPD, which might be causally involved in disease progression. However, there are only limited studies available that prospectively identified patients at risk for small airway disease. Our intention is to investigate the early phase of the disease. In addition, we thereby want to build up a well-defined study population of patients in an early phase of the disease with a rapid decrease in lung function as measured by oscillometry and multiple breath washout (MBW)-testing. In addition, it is our goal to identify patients in an early stage of disease and patients at risk of fast progression and/or rapid decline in lung function.
