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. 2022 Oct 6;9(1):e001385. doi: 10.1136/bmjresp-2022-001385

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© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

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Flow chart of the retrospective study. This figure shows the selection of patients according to eligibility criteria. One participant did not meet any of the group definition and was therefore not included in the grouping analysis. AL, airflow limitation; COPD, chronic obstructive pulmonary disease; FEF_25-75, forced expiratory flow between 25% and 75% of vital capacity; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; PPY, pack per year.