Table 1 Baseline characteristics of currently smoking subjects*

Age, years

53.8 ± 6.9

59.2 ± 7.8

<.0001

Male, n (%)

276(54.4)

185(55.2)

0.82

White, n (%)

245(48.3)

244(72.8)

<.0001

BMI, kg/m²

28.5 ± 5.9

27.1 ± 5.8

0.001

FTND score

4.6 ± 2.5

4.7 ± 2.4

0.49

Nicotine dependence (FTND ≥6), n (%)

196(38.7)

133(39.7)

0.76

Smoking amount, pack-years

37.2 ± 19.2

51.7 ± 28.8

<.0001

Average number of cigarette smoked per day

20.2 ± 8.9

23.8 ± 10.8

<.0001

Cigarettes/day, current

16.9 ± 9.8

17.3 ± 10.8

0.56

Smoking starting age, years

17.0 ± 5.3

16.4 ± 4.8

0.09

FEV1/FVC, ratio

0.79 ± 0.05

0.53 ± 0.12

<.0001

FEV1, % of predicted

97.6 ± 12.3

55.2 ± 16.4

<.0001

% Emphysema at -950 HU^‡, %

1.84 ± 2.21

8.81 ± 9.75

<.0001

% Gas trapping, %

10.5 ± 9.9

32.9 ± 19.3

<.0001

Pi₁₀

3.75 ± 0.12

3.81 ± 0.12

<.0001