Table 1

Characteristics of subjects

Subjects	Sex (M/F)	Age (years)	Smoking history (packs/year)	FEV₁(% pred)	FEV₁/FVC (%)
p<0.0005 v asymptomatic smokers; p<0.05 v asymptomatic smokers; **p<0.0005 v COPD patients (unpaired t test); predicted values from reference 20. †Symptomatic smokers with normal lung function.
COPD patients
1	M	74	58	56	64
2	M	68	43	68	72
3	M	84	61	62	69
4	M	63	16	78	75
5	M	58	31	75	70
6	M	66	78	68	67
7	M	57	88	78	69
8	M	75	100	77	62
Mean		68	59	70*	69**
SE		3	10	3	1

Bronchitis patients†
1	M	69	25	89	66
2	M	57	94	91	70
3	M	65	52	80	84
4	M	75	55	97	71
5	M	58	46	83	72
6	M	67	49	99	74
7	M	58	32	105	82
Mean		64	50	92***	74
SE		3	8	3	2

Asymptomatic smokers
1	M	72	65	108	72
2	M	81	60	116	91
3	M	70	54	86	82
4	M	58	22	94	87
5	M	56	29	101	75
6	M	65	47	97	80
7	F	44	21	104	93
8	M	67	31	83	69
9	M	65	48	86	76
Mean		64	42	97	79
SE		4	4	4	2

Non-smokers
1	F	68	0	92	81
2	M	61	0	101	87
3	F	68	0	102	84
4	F	72	0	119	80
5	F	64	0	123	83
6	M	79	0	127	ND
Mean		69	0	110	86
SE		3	0	6	3