Table 1 Study population characteristics; demographics, smoking habits, respiratory symptoms and biomarker levels, comparing non-COPD and COPD and also presented by GOLD stages

Female, n (%)

447 (47)

248 (42)

0.038

155 (41)

87 (46)

6 (23)

Age (years), median (IQR)

67 (55–71)

69 (57–71)

0.015

69 (56–71)

69 (58–71)

70 (64–79)

BMI (kg/m2), median (IQR)

26.8 (24.3-29.7)

26.1 (23.5-28.7)

<0.001

25.8 (23.6-28.4)

26.5 (23.5-29.0)

27.6 (21.7-29.4)

Pack years, median (IQR)

0.8 (0–12)

14 (0–27)

<0.001

8.6 (0–24)

18.5 (2.0-32.3)

26.9 (14.8-42.5)

Non-smoker, n (%)

443 (47)

149 (25)

<0.001

113 (30)

34 (18)

2 (8)

Ex smoker, n (%)

384 (41)

247 (42)

0.676

153 (40)

75 (41)

19 (73)

Current smoker, n (%)

120 (13)

197 (33)

<0.001

111 (29)

81 (43)

5 (19)

Productive cough, n (%)

212 (22)

238 (40)

<0.001

125 (33)

93 (49)

20 (77)

mMRC dyspnoea score ≥2, n (%)

46 (5)

75 (13)

<0.001

17 (5)

40 (22)

18 (69)

FEV₁% predicted^†, median (IQR)

1.03 (0.93-1.13)

0.85 (0.73-0.96)

<0.001

0.93 (0.86-1.01)

0.70 (0.64-0.75)

0.44 (0.37-0.47)

MMP-9 (ng/ml), median (IQR)

505 (364–606)

535 (315–653)

0.017

513 (241–626)

559 (379–662)

647 (565–692)

TIMP-1 (ng/ml), median (IQR)

316 (229–490)

304 (227–439)

0.252

311 (237–467)

294 (218–425)

298 (247–383)

Ratio of MMP-9/TIMP-1, median (IQR)

1.36 (0.85-2.09)

1.5 (0.83-2.32)

0.168

1.46 (0.78-2.18)

1.48 (0.9-2.5)

1.95 (1.47-2.79)