Abstract Introduction We recently developed a multidimensional diagnostic schema for COPD that incorporates symptoms, imaging abnormalities, and spirometry. This schema identifies additional individuals with COPD who do not have spirometric airflow obstruction. In this study, we aimed to evaluate the structural changes associated with those newly diagnosed and those potentially missed by the multidimensional diagnostic schema for COPD. Methods We analyzed participants from the multicenter COPDGene cohort of current and former smokers aged 40-85 years. Using the multidimensional diagnostic schema, COPD was diagnosed either by (1) major diagnostic category: presence of the major criterion (airflow obstruction: FEV1/FVC 0.7) and at least 1 of 5 minor criteria (emphysema or bronchial wall thickening on computed tomography (CT), dyspnea, poor respiratory quality of life, and chronic bronchitis); or (2) minor diagnostic category: presence of at least 3 of 5 minor criteria. Four categories were created: No COPD (no airflow obstruction and no COPD using the new schema), New COPD (No airflow obstruction but met minor diagnostic criteria), Excluded (airflow obstruction but no COPD using new schema), and COPD (airflow obstruction and COPD using the new schema). We compared structural changes on CT of both airway wall (Pi10 and PiSlope) and lumen (Total Airway Count, Airway Fractal Dimension, and Airway Tapering Slope) as well as lung parenchyma (Jacobian Determinant and Normal Density Expiratory/Inspiratory Ratio) across categories, with No COPD as the reference category. Results Among 9,416 participants, 811 (15.4%) of 5250 individuals without airflow obstruction were newly classified as having COPD by minor diagnostic category, and 282 (6.8%) of 4166 individuals with airflow obstruction were classified as not having COPD. Compared to those without COPD, newly diagnosed individuals had significantly different imaging measures of airway wall thickness and lumen, as well as the Jacobian determinant, an estimate of lung elasticity (Table). In contrast, most imaging measures were similar between individuals without COPD and those who had airflow obstruction but were excluded from the diagnosis. Conclusions We demonstrated substantial structural changes on imaging in individuals newly labelled as COPD using the multidimensional diagnostic schema. Those excluded from diagnosis did not differ substantially from those without COPD. This abstract is funded by: This work was supported by NHLBI R01 HL151421. The COPDGene study (NCT00608764) is supported by grants from the NHLBI (U01HL089897 and U01HL089856), by NIH contract 75N92023D00011, and by the COPD Foundation through contributions made to an Industry Advisory Committee that has included AstraZeneca, Bayer Pharmaceuticals, Boehringer-Ingelheim, Genentech, GlaxoSmithKline, Novartis, Pfizer and Sunovion.
Sthanam et al. (Fri,) studied this question.