Table 2 COPD medical history, lung function parameters and mMRC Scale score at enrollment

COPD duration (yrs) (mean ± SD)

7.8 ± 6.5

7.7 ± 6.5

8.0 ± 6.3

8.7 ± 8.9

Age at COPD diagnosis (yrs) (mean ± SD)

63.6 ± 9.1

63.9 ± 9.4

63.5 ± 8.1

61.4 ± 11.5

N of COPD exacerbations/year (5 years before baseline) median (IQR)

2.0 (1.0–3.0)

2.0 (1.0–4.0)

1.0 (0.0–2.0)

3.0 (1.0–5.0)

 group A

155 (25.6)

76 (21.7)

66 (30.7)

12 (37.5)

 group B

187 (30.9)

133 (37.9)

43 (20.0)

7 (21.9)

 group C

126 (20.8)

59 (16.8)

57 (26.5)

8 (25.0)

 group D

138 (22.8)

83 (23.6)

49 (22.8)

5 (15.6)

FEV1 (L)

Median (IQR)

n = 535

n = 298

n = 200

n = 29

1.5 (1.2–2.0)

1.6 (1.2–2.0)

1.5 (1.1–2.0)

1.5 (1.2–1.9)

FEV1 of the predicted (%)

Median (IQR)

n = 537

n = 300

n = 200

n = 29

63.9 (50.0–80.0)

66.9 (51.0–81.8)

61.9 (48.1–78.0)

58.4 (48.3–77.2)

FVC (L)

Median (IQR)

n = 536

n = 299

n = 200

n = 29

2.7 (2.2–3.4)

2.6 (2.2–3.3)

2.9 (2.2–3.5)

2.5 (2.1–3.1)

FEV1/FVC (%)

Median (IQR)

n = 537

n = 300

n = 200

n = 29

59.7 (49.0–69.0)

62.0 (52.0–70.0)

56.0 (45.0–66.6)

62.3 (53.0–68.1)

RV (L)

Median (IQR)

n = 291

n = 130

n = 138

n = 21

3.2 (2.6–4.2)

2.9 (2.3–3.7)

3.5 (2.9–4.8)

3.4 (2.8–4.9)

IC (L)

Median (IQR)

n = 306

n = 143

n = 138

n = 24

2.6 (2.1–3.4)

2.6 (2.1–3.3)

2.7 (2.1–3.5)

2.4 (2.2–3.3)

TLC (L)

Median (IQR)

n = 286

n = 128

n = 135

n = 21

6.4 (5.4–7.3)

6.0 (4.9–6.9)

6.8 (5.8–7.6)

6.5 (5.7–7.3)

RV/TLC

Median (IQR)

n = 289

n = 128

n = 138

n = 21

0.5 (0.4–0.6)

0.5 (0.4–0.6)

0.6 (0.5–0.6)

0.6 (0.5–0.6)

DLCO of the predicted (%)

Median (IQR)

n = 205

n = 98

n = 92

n = 15

68.0 (51.0–83.0)

69.5 (59.0–87.0)

63.0 (46.8–76.5)

76.7 (48.0–81.5)

mMRC Scale score

n = 577

n = 334

n = 205

n = 30

 Median (IQR)

1.0 (1.0–2.0)

1.0 (1.0–2.0)

1.0 (1.0–2.0)

1.0 (1.0–2.0)

  ≥ 2 (N, %)

262 (45.4)

150 (44.9)

97 (47.3)

11 (36.7)