Table I.

Study Population¹

		Healthy smokers²			COPD smokers³
Parameter	Non-smokers	All	Who continued smoking	Who quit	All	Who continued smoking	Who quit
n	28	61	44	17	49	31	18
Gender (M/F)	15/13	47/14	37/7	10/7	46/3	30/1	16/2
Ethnicity (B/W/O)⁴	10/7/11	33/9/19	23/7/14	10/2/5	27/12/10	18/6/7	9/6/3
Age	37 ± 11	44 ± 9	44 ± 9	45 ± 10	53 ± 8	53 ± 7	53 ± 9
BMI	27 ± 5	28 ± 5	27 ± 4	30 ± 4	27 ± 4	25 ± 3	29 ± 5
Smoking history
Pack-yr	–	23 ± 12	24 ± 12	20 ± 8	32 ± 14	32 ± 15	34 ± 12
Pack per day	–	0.8 ± 0.6	1.0 ± 0.6	0.6 ± 0.2	0.8 ± 0.4	0.8 ± 0.5	0.8 ±0.3
Age of initiation	–	16 ± 3	16 ± 3	16 ± 3	16 ± 3	16 ± 3	16 ± 3
Urine cotinine (ng/ml)	–	1693 ± 961	1828 ± 930	1323 ± 979	1747 ± 980	1953 ± 959	1393 ± 938
Subjects with emphysema (n, %)⁵	1 (4%)	0 (0%)	0 (0%)	0 (0%)	13 (27%)	9 (29%)	4 (22%)
Pulmonary function⁶
FEV1	106 ± 11	109 ± 11	109 ± 10	107 ± 13	85 ± 16	87 ± 16	82 ± 17
FVC	107 ± 11	111 ± 10	110 ± 10	111 ± 11	108 ± 16	109 ± 17	105 ± 15
FEV1/FVC	83 ± 5	80 ± 5	81 ± 4	79 ± 6	63 ± 6	64 ± 6	63 ± 7
TLC	99 ± 16	96 ± 12	95 ± 12	96 ± 10	99 ± 12	100 ± 13	99 ± 10
DLCO	91 ± 11	89 ± 8	89 ± 9	90 ± 6	71 ± 14	68 ± 13	77 ± 15
GOLD stage (I/II)	–	–	–	–	31/18	20/11	11/7

Data are presented as mean ± standard deviation; all parameters recorded at baseline; health/disease state based on screening and medical history and smoking status based on self-reported history and urine nicotine metabolite levels (detailed in Supplemental Methods); nonsmokers were comparable to all healthy smokers and all COPD smokers in ethnicity, BMI and all pulmonary function (p>0.1, all comparisons), except for FEV1 and DLCO that were lower in all COPD smokers (p<10⁻⁷, both comparisons) and FEV1/FVC, that was lower in all healthy smokers and, by definition, in all COPD smokers (p<0.02, both comparisons). Nonsmokers were younger than all healthy smokers and all COPD smokers (p<0.002, both comparisons) and there were less female COPD smokers than female nonsmokers (p<0.0002). There were more COPD smokers with emphysema compared to nonsmokers (p<10⁻⁴); All healthy smokers were comparable to all COPD smokers in ethnicity, age, BMI, all smoking history parameters (p>0.3, all comparisons) except for pack-yr that was lower in all healthy smokers (p<10⁻³). FVC and TLC were comparable (p>0.07, both comparisons), but FEV1, DLCO and, by definition, FEV1/FVC were lower in all COPD smokers (p<10⁻¹², all comparisons). There were fewer females among all COPD smokers than among all healthy smokers (p<0.04). There were more COPD smokers with emphysema compared to healthy smokers (p<10⁻⁴).

Healthy smokers who continued smoking had urine cotinine ≥ 104 ng/ml (see Supplemental Methods for details) at baseline, 3,6, and 12 months. Healthy smokers who quit had undetectable urine nicotine and cotinine levels at 3, 6 and 12 months. The healthy smokers who continued smoking were comparable to those who quit in age, ethnicity, all smoking history (p>0.3, all comparisons), except for pack per day that was lower in those who quit (p<0.03), and comparable in all pulmonary function (p>0.1). There were more females and the BMI was higher in the healthy smokers who quit group (p<0.04, both comparisons).

Gold stage defined by GOLD criteria¹; see Supplemental Methods for details for subjects on medications; several of those treated were on multiple classes of medications; COPD smokers who continued smoking had urine cotinine ≥ 104 ng/ml at baseline, 3, 6 and 12 months; COPD smokers who quit had undetectable urine nicotine and cotinine levels at 3, 6 and 12 months; The COPD smokers who continued smoking were comparable to those who quit in age, gender, ethnicity, all smoking history and all pulmonary function (p>0.3, all comparisons), except for DLCO that was lower in the COPD who continued smoking compared to those who quit (p<0.03). The BMI was lower in the COPD who continued smoking vs those who quit (p<0.002). There was no difference in the number of subjects with emphysema between the COPD smokers who quit smoking and those who continued smoking (p>0.6).

⁴

B=Black, W=White, O= Other.

⁵

Chest high resolution computed tomography (HRCT); % emphysema at −950 Hounsfield Units (HU); Emphysema defined as >5% lung volume, see Supplemental Methods for details.

⁶

Pulmonary function testing parameters are given as % of predicted value with the exception of FEV1/FVC, which is reported as % observed; FVC - forced vital capacity; FEV1 - forced expiratory volume in 1 sec; TLC - total lung capacity; DLCO - diffusing capacity.