Symptoms of COPD in the absence of airflow obstruction are more indicative of pre-COPD than overdiagnosis

BACKGROUND: Dysfunction of the small airways is a precursor of COPD but is not detectable on standard spirometric testing until significant destruction has occurred. A proportion of COPD patients have a forced expiratory volume in 1 s (FEV(1))/forced vital capacity (FVC) <0.7 which is greater than the lower limit of normal (LLN), when adjusted for their age and sex. It is not understood whether this group of patients, known as "discordant COPD", are representative of "early COPD" or overdiagnosis. METHODS: We sought to characterise discordant COPD (disCOPD) using radiology, lung function, serum biomarkers, activity monitoring and quality-of-life scores, comparing with COPD patients with an FEV(1)/FVC <0.7 and