Discordant airways obstruction – subjects in between spirometric definitions of COPD – an analysis of the CLARA Studies

<bold>Background:</bold> Airways obstruction by spirometry can be defined using the fixed ratio of 0.70 or the lower limit of normal (LLN) for FEV1/FVC – this may have implications for diagnosis and treatment of COPD. <bold>Methods:</bold> We pooled the data of two national, cross-sectional studies (CLARA I & II) conducted in offices of pulmonologists and general practitioners in Austria (data collection 09-12/2018 and 09/2021-01/2022). A demographic questionnaire and the St. George’s Respiratory Questionnaire for COPD patients (SGRQ-C) were used. Inclusion criteria were a physician’s diagnosis of COPD and age ≥40 years. Subjects with a history of major lung surgery, lung cancer or COPD exacerbation within the last four weeks were excluded. Discordant airways obstruction was defined as postbronchodilator FEV1/FVC ratio above the LLN but below the fixed ratio of 0.70. <bold>Results:</bold> Of 1.874 patients included, 393 patients were unobstructed according to both definitions and were therefore excluded. Finally, 1480 patients (37.3% female; mean age 66.4±8.8(SD) years; mean BMI 26.7±5.5(SD) kg/m²; mean FEV1%pred 52.7±16.9(SD)) were analyzed. SGRQ-C total score was 41.2. 302 patients (20.4%) had discordant airways obstruction. These patients were more often male, significantly older, and less symptomatic (cough, phlegm and dyspnea); they had a higher BMI, less exacerbations, a better FEV1%pred, and lower SGRQ-C-scores. In a multivariate linear regression model, patient with discordant airways obstruction were significantly older, more often male, had a higher BMI, and a better FEV1%pred. <bold>Conclusions:</bold> Patients with discordant airways obstruction are less symptomatic and report fewer exacerbations.