Chronic Obstructive Pulmonary Disease (COPD) is diagnosed using the FEV1/FVC, which has limitations as a diagnostic test. We assessed the validity of several measures derived from the expiratory phase of the flow-volume curve obtained from spirometry to diagnose COPD: the slopes corresponding to the volume expired after the 50% and 75% of the FVC, the slope formed between the Peak Expiratory Flow (PEF) and the FVC, and the area under the expiratory flow/volume curve.
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