Table 1.

Components of Operational Definition for Early Chronic Obstructive Pulmonary Disease

Required	One or More of the Following:
<50 yr of age	FEV1/FVC less than lower limit of normal
≥10 pack-years smoking history	Compatible computed tomography abnormalities (visual emphysema, air trapping, or bronchial thickening graded mild or worse)
	Evidence of accelerated FEV1 decline (≥60 ml/yr)

Exclusion criteria include other known chronic lung diseases, including interstitial lung diseases, but not asthma (see text).