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

Abstract

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 (FEV1)/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. 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 FEV1/FVC <0.7 and <LLN and healthy, age-matched controls. Six out of eight serum biomarkers were significantly different in the disCOPD group versus healthy controls, as were the scores of all four quality-of-life questionnaires. Activity monitoring revealed similar levels of sedentary time between the disCOPD group and concordant COPD (conCOPD). Computed tomography analysis showed less involvement of small airway dysfunction and emphysema in the disCOPD group versus conCOPD. Collectively, our findings support the hypothesis that disCOPD is a clinically relevant phenomenon that represents a pre-COPD state. Identification of such patients is important for early intervention and management before progression to fully established COPD.