TABLE 2.

DEMOGRAPHIC CHARACTERISTICS OF CONTROL SUBJECTS, SMOKERS WITHOUT COPD, AND SMOKERS WITH COPD

	Control Subjects (n = 12)	Smokers/COPD-Negative (n = 11)	Smokers/COPD-Positive (n = 18)	P*
Age (years), median	50 (45–63)	53 (40–55)	56 (49–70)	ns
Male sex (%)	3 (25)	3 (27)	8 (44)
Race (%)
Caucasian	9 (75)	10 (91)	15 (84)
African American	0 (0)	0 (0)	1 (5)
Hispanic	0 (0)	1 (9)	2 (11)
Asian	3 (25)	0 (0)	0 (0)
Pack years of smoking (median)	0	20 (12–33)	32 (16–68)	<0.0001

Definition of abbreviation: ns, non significant.

Medians are given with interquartile ranges.

^*Comparison between all three groups, according to Kruskal-Wallis analysis.