Table 2– Clinical characteristics of smokers with and without chronic obstructive pulmonary disease (COPD)

Age years	Smoking history pack-years	Smoking cessation	FEV₁/FVC % (LLN)	FEV₁ % pred	Emphysema score on HRCT (0–30)
Smokers without COPD
68	41	9 years	89	81	0
73	37	4 years	82	128	0
73	56	8 years	80	123	0
47	3	22 years	82	103	0
39	20	2 months	90	122	0
78	168	7 days	80	152	0
67	10	27 years	91	123	0
70	90	9 years	76	94	0
63	65	8 days	75	71	0
31	17	2 months	82	101	0
56	35	10 years	83	107	0
75	24	2 months	81	141	0
55	73	1 month	82	93	0
Smokers with COPD
76	20	16 years	60 (67)	126	7
77	100	3 years	59 (67)	112	14
77	69	2 years	57 (67)	111	13
76	56	1.5 months	62 (67)	97	10
54	45	3 months	69 (72)	96	13
77	40	12 years	64 (67)	96	14
61	56	1 year	59 (70)	90	12
75	81	2 months	64 (68)	80	10
54	72	3 months	53 (72)	53	25
53	95	2 years	34 (71)	24	24

FEV₁: forced expiratory volume in 1 s; FVC: forced vital capacity; LLN: lower limit of normal; % pred: % predicted; HRCT: high-resolution computed tomography.