Table 1.

Characteristics of subjects (n = 12/group)

	Healthy non-smokers	Current smokers without COPD	Current smokers with COPD
Age, years	53 ± 5	49 ± 6*	56 ± 5
Gender (male)	6	5	10
Race†
Caucasian	8	4	11
African American	2	8	1
Other	2	0	0
FEV1, % predicted		88 ± 15*	59 ± 19
FEV1/FVC, %		80 ± 5*	53 ± 12

^*P < 0·05, chronic obstructive pulmonary disease (COPD) versus smokers without COPD (post-bronchodilator values).

^†The proportion of racial composition in groups is different, P = 0·048. Data presented as mean ± standard deviation. FEV₁ = forced expiratory volume in 1 s.