Table 2 Comparison of annual change in FEV₁ between patients with COPD classified based on smoking status at baseline and comorbidity during the 5-year follow-up period

Number of participants

13

52

25

40

24

41

18

47

17

48

Age

66.5 (2.9)

70.4 (1.0)

71.1 (1.7)

68.7 (1.2)

70.0 (2.0)

69.0 (1.1)

72.8 (1.6)

68.5 (1.2)

72.4 (1.4)

68.7 (1.2)

Sex; Male:Female

9:4

44:8

19:6

34:6

18:6

35:6

16:2

37:10

15:2

40:8

Body mass index

22.1 (0.4)

22.5 (0.4)

22.7 (0.6)

22.3 (0.5)

22.9 (0.7)

22.2 (0.4)

23.4 (0.8)

22.1 (0.4)

21.9 (0.8)

22.6 (0.4)

Smoking history (pack-years)

49.4 (5.2)

52.3 (2.0)

50.5 (3.0)

52.5 (2.4)

46.4 (1.4)

54.9 (2.8)

49.8 (2.1)

52.5 (2.5)

55.9 (4.7)

50.3 (1.9)

Current: Former

8:17

4:36

10:14

3:38**

3:15

10:37

3:14

10:38

Laboratory values

Neutrophil in blood (count/µl)

4152 (285)

3740 (150)

4166 (220)

3594 (159)*

4238 (208)

3579 (163)*

4367 (237)

3614 (151)*

3688 (283)

3870 (151)

Eosinophil in blood (count/µl)

220.9 (34.0)

200.8 (18.0)

227.3 (25.1)

189.7 (20.3)

248.2 (29.4)

179.4 (17.4)*

220.5 (40.4)

198.7 (15.8)

169.2 (27.0)

217.4 (19.0)

Total IgE in serum (IU/ml)

392.7 (251.7)

417.2 (120.0)

468.4 (224.6)

374.9 (177.6)

686.6 (252.4)

179.4 (78.4)

680.1 (297.9)

309.7 (184.4)

451.6 (171.0)

398.4 (133.3)

mMRC

1.2 (0.1)

1.3 (0.1)

1.5 (0.1)

1.1 (0.1)**

1.4 (0.1)

1.2 (0.1)

1.4 (0.1)

1.2 (0.1)

1.3 (0.1)

1.3 (0.1)

CAT

7.3 (1.9)

5.6 (0.6)

7.3 (1.1)

5.1 (0.6)

6.9 (1.3)

5.4 (0.6)

7.7 (1.5)

5.3 (0.6)

5.4 (0.7)

6.2 (0.8)

FEV1

Baseline (L)

1.54 (0.12)

1.69 (0.09)

1.41 (0.09)

1.83 (0.10)**

1.46 (0.09)

1.78 (0.10)*

1.46 (0.09)

1.74 (0.09)

1.53 (0.13)

1.71(0.09)

After 5 years (L)

1.21 (0.12)

1.66 (0.09)*

1.25 (0.08)

1.79 (0.10)**

1.31 (0.10)

1.72 (0.10)**

1.36 (0.10)

1.65 (0.10)

1.45 (0.12)

1.61 (0.09)

Annual change (ml/year)

 − 66.2 (7.6)

 − 5.7 (2.8)**

 − 31.5 (7.8)

 − 8.9 (3.7)**

 − 30.2 (8.0)

 − 10.8 (4.0)*

 − 19.9 (8.8)

 − 17.2 (4.5)

 − 14.6 (0.4)

 − 19.1 (5.0)

%FEV1

Baseline (%)

62.4 (3.8)

62.9 (2.3)

58.3 (3.5)

65.8 (2.3)

57.7 (2.6)

65.8 (2.7)*

58.0 (2.9)

64.6 (2.5)

58.8 (4.5)

64.2 (2.2)

After 5 years (%)

52.0 (3.9)

65.9 (2.4)**

55.8 (3.6)

68.0 (2.4)**

55.0 (2.9)

67.9 (2.7)**

57.8 (33.3)

65.2 (2.7)

60.1 (4.6)

64.2 (2.4)

Annual change (%/year)

 − 2.1 (0.20)

0.6 (0.12)**

 − 0.49 (0.35)

0.44 (0.17)**

 − 0.53 (0.37)

0.42 (0.16)**

 − 0.05 (0.40)

0.11 (0.19)

0.26 (0.24)

0.00 (0.23)

IOS

R5 (kPa/L/s)

0.32 (0.01)

0.28 (0.01)

0.33 (0.03)

0.26 (0.01)**

0.33 (0.02)

0.26 (0.01)**

0.29 (0.02)

0.29 (0.01)

0.28 (0.02)

0.29 (0.02)

R20 ( kPa/L/s)

0.24 (0.02)

0.20 (0.01)

0.22 (0.01)

0.30 (0.01)

0.23 (0.01)

0.20 (0.01)*

0.20 (0.01)

0.21 (0.01)

0.19 (0.01)

0.21 (0.01)

R5-R20 ( kPa/L/s)

0.09 (0.01)

0.08 (0.01)

0.11 (0.01)

0.06 (0.01)**

0.11 (0.01)

0.07 (0.01)*

0.09 (0.02)

0.08 (0.01)

0.09 (0.02)

0.08 (0.01)

X5 (kPa/L/s)

 − 0.12 (0.01)

 − 0.13 (0.01)

 − 0.15 (0.02)

 − 0.11 (0.01)*

 − 0.15 (0.02)

 − 0.12 (0.01)

 − 0.13 (0.02)

 − 0.13 (0.01)

 − 0.13 (0.02)

 − 0.13 (0.01)

Fres (Hz)

20.3 (1.4)

18.3 (0.8)

21.4 (1.0)

16.5 (0.8)**

20.7 (1.0)

17.5 (1.0)*

19.1 (1.4)

18.5 (0.9)

17.8 1.6)

19.0 (1.8)

AX (kPa/L)

0.99 (0.17)

0.90 (0.13)

1.27 (0.20)

0.64 (0.09)**

1.21 (0.18)

0.75 (0.13)*

0.95 (0.22)

0.92 (0.12)

0.97 (0.21)

0.90 (0.12)