Table 1. Summary of subject demographics, smoking history, and spirometry.

Group	Control	COPD GOLD II	COPD GOLD IV
Subjects, n	35	7	5
Sex: M,F	14, 21	3, 4	0, 5
Age, yr	65(10)	70 (6)	61 (8)
Smoking, pack-years (active and former)	28(12)	41 (10)	45 (9)
Smoking status: never, active, former	8, 1, 26	0, 0, 7	0, 0, 5
FEV1, % pred	94(17)	57 (7)	27 (17)
DLco, % pred	74 (14)	63(10)	31 (4)

Definition of abbreviations: % pred = percentage of the predicted value; COPD = Chronic Obstructive Pulmonary Disease

Data are represented as mean (SD)