Impaired diffusing capacity and COPD incidence in adults with symptoms and normal spirometry.

Background: Impaired diffusing capacity of the lung (DLCO) in the absence of post-bronchodilator (BD) airflow obstruction has been proposed as a marker of 'Pre-COPD'. However, the relationship between impaired DLCO and subsequent lung function decline and COPD incidence has not been examined in-depth.

Methods: We conducted an observational study of adults aged between 40 and 70 years who were evaluated at a multi-centre lung function laboratory in Australia between 2014 and 2024.