Table 2 Mean (SD) characteristics of the COPD cohorts and resistant smokers.

Parameter	COPD (N = 230)	Resistant smokers (N = 210)	Differences (p value)
% men	59%	63%	0.88
Age (years)	65 (10)	59 (13)	<0.001
Pack years	50 (29)	42 (25)	0.002†
Cigarettes/day	24 (15)	24 (12)	0.76*
FEV1 (l)	1.6 (0.56)	2.9 (0.73)	0.01
FEV1 (% predicted)	42 (18)	96% (10)	<0.001
FEV1/FVC	51 (15)	82 (8)	<0.001

*There were also no significant differences in the age started smoking, age stopped smoking, or duration of smoking.

†After correcting for age there was no difference in the pack years.