Table 1– Subject demographics

	Never-smokers	Smokers	COPD
Subjects n	40	49	77
Sex female/male n/n	29/11	24/25	32/45
Age years	64.8±13.3	61.5±9.2	66.2±6.7
FEV₁ L	2.04±0.55	2.40±0.62	1.75±0.55
FEV₁ % pred	106.5±16.2	88.7±17.8	68.3±14.3
FVC	2.71±0.56	3.31±0.55	3.03±0.90
FEV₁/FVC ratio	79.2±12.8	74.3±8.1	58.8±8.7
Smoking history pack-years	NA	47.9±21.8	53.1±26.8

Data are presented as mean±sd, unless otherwise stated. COPD: chronic obstructive pulmonary disease; FEV1: forced expiratory volume in 1 s; % pred: % predicted; FVC: forced vital capacity; NA: not applicable.