Fig. 1

Study flow ^aThis figure illustrates the sample determination from the Population Assessment of Tobacco and Health Study for the prevalence and incidence models (Tables 2 and 3) for COPD ^bCOPD Chronic Obstructive Pulmonary Disease, defined as self-report of emphysema, chronic bronchitis, or COPD; prevalence and incidence models. ^cWeights adjust for non-response. ^dOther non-asthma or COPD respiratory diseases