Table 2. Prevalence of airway obstruction according to the GOLD criteria^*.

GOLD, Global Initiative for Chronic Obstructive Lung Disease.

^*GOLD criteria: forced expiratory volume in one second/forced vital capacity ratio<0.7. ^†No. of subjects who have airway obstruction in spirometry. ^‡Data from the 5th Korea National Health and Nutritional Examination Survey. ^§Includes former and current smokers. ^∥P-value is for trend.