Table 2—

Study characteristics

Parameter	Lung cancer	COPD	Control smokers
Subjects n	454	458	488
Males	53	59	60
Age yrs	69±10	66±9	65±10
Smoking history
Current smoker	35	40	48
Age started smoking yrs	18±4	17±3	17±3
Length of time smoked yrs	41±12	42±11	35±11
Pack-yrs	41±25*	47±20*	40±19*
Cigarettes·day⁻¹	20±10	23±9	24±11
Time since quitting yrs	11.4±6.7	9.8±7.4	13.9±8.1
History of other exposures
Work dust	63*	59*	47*
Work fume	41	40	38
Asbestos	23*	22*	16*
Family history
COPD	33	37	28
Lung cancer	19*	11*	9*
Lung function
FEV₁ L	1.86±0.48*	1.25±0.48*	2.86±0.68*
FEV₁ % pred	73*	46*	99*
FEV₁/FVC	64±13*	46±8*	78±7*
Spirometric COPD^#	57*	100*	0*

Data are presented as % or mean±sd, unless otherwise stated. COPD: chronic obstructive pulmonary disease; FEV₁: forced expiratory volume in one second; % pred: % predicted; FVC: forced vital capacity. ^#: according to Global Initiative for Chronic Obstructive Lung Disease stage 2. *: p<0.05.