COPD
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The objective of this study was to evaluate the definitions for classification of chronic obstructive pulmonary disease (COPD) recommended by the American Thoracic Society (ATS) and the Global Initiative for Chronic Obstructive Lung Disease (GOLD). Using data from the U. S. population-based third National Health and Nutrition Examination Survey (NHANES III), we compared the number of individuals in the U. ⋯ Based on our estimation, approximately 0.9 million (26%) of symptomatic individuals out of the 3.6 million U. S. adults aged 20-49 years who have airflow obstruction (FEV1/FVC < LLN and FEV1 < LLN definition) may have undiagnosed respiratory disease. In conclusion, using the FEV1/FVC < 0.70 criterion will substantially under-diagnose airway obstruction in younger individuals and substantially over-diagnose COPD in older individuals.