Subjects with Discordant Airways Obstruction: Lost between Spirometric Definitions of COPD

Abstract

Background. Since the FEV1/FVC ratio declines with age, using the fixed ratio of 0.70 leads to overdiagnosis of COPD in older populations and underdiagnosis among young adults.Objective. To evaluate whetherdiscordant obstructive cases(FEV1/FVC < 0.70 but ≥LLN) are a healthy population or have clinical features that would place them at increased risk.Methods. We used post-bronchodilator spirometry data from the population-based Austrian Burden of Obstructive Lung Disease (BOLD) study. Those with post-bronchodilator FEV1/FVC ratio <LLN and <0.70 were defined asconcordant obstructive cases. Participants with post-bronchodilator FEV1/FVC ratio ≥LLN but <0.70 were defined asdiscordant obstructive cases.Results.Discordant obstructive caseswere more likely to be older, male and never-smokers. Additionally they had less respiratory symptoms and less severe impairment of FEV1. However,discordant obstructive casesreported significantly more often a diagnosis of heart disease than subjects with normal lung function (27.2% vs 7.3%,P=.015).Conclusion. The clinical profile of discordant obstructive cases includes potentially important comorbid disease.