Table 1 Profiles of the four participant groups

Number of subjects

23

13

50

20

Age (yr)

66.7 ± 9.0

66.5 ± 11.6

68.5 ± 7.2

68.2 ± 7.8

Gender^a (no. of males; %)

15 (65.2)

12 (92.3)

47 (94.0)

14 (70.0)

Body mass index (kg/m²)

22.1 ± 2.4

23.0 ± 2.8

21.9 ± 3.1

19.8 ± 3.8^†

Smoking status^a

Non / Ex / Cu (no.)

23 / 0 / 0

0 / 4 / 9

0 / 33 / 17

0 / 14 / 6

Smoke index (pack-yrs)

0

40.0 ± 18.2^***

59.3 ± 30.3^***

52.2 ± 27.0^***

Comorbidities^a

Hypertension (no; %)

7 (30.4)

4 (30.8)

13 (26.0)

4 (20.0)

Diabetes (no; %)

5 (21.7)

1 (7.7)

11 (22.0)

6 (30.0)

Duration of COPD (yr)

N/A

N/A

5.3 ± 3.9

5.5 ± 4.4

GOLD stage^a

I / II / III / IV (no.)

N/A

N/A

7 / 22 / 17 / 4

2 / 4 / 8 / 6

Lung function parameters

Before bronchodilator

FVC (L)

3.5 ± 0.9

3.6 ± 0.7

3.4 ± 0.8

2.7 ± 0.9^*†‡

%FVC

108.5 ± 17.0

105.6 ± 19.3

98.8 ± 18.3

86.4 ± 22.2^**†

FEV₁ (L)

2.6 ± 0.6

2.6 ± 0.5

1.5 ± 0.6^***†††

1.1 ± 0.7^***†††

%FEV₁

100.8 ± 14.3

94.9 ± 20.1

54.9 ± 20.8^***†††

44.8 ± 24.9^***†††

FEV₁/FVC (%)

77.2 ± 6.9

73.8 ± 5.2

44.4 ± 12.7^***†††

41.0 ± 16.2^***†††

After bronchodilator

FVC (L)

3.4 ± 0.9

3.5 ± 0.7

3.4 ± 0.8

2.6 ± 1.0^*†‡

%FVC

108.0 ± 17.4

104.3 ± 18.0

99.3 ± 18.5

84.9 ± 23.5^**†‡

FEV₁ (L)

2.7 ± 0.6

2.7 ± 0.4

1.6 ± 0.6^***†††

1.2 ± 0.7^***†††

%FEV₁

103.0 ± 15.5

96.5 ± 19.9

56.4 ± 20.8^***†††

45.3 ± 25.0^***†††

FEV₁ / FVC (%)

79.2 ± 6.5

76.0 ± 5.9

45.6 ± 13.4^***†††

42.3 ± 15.9^***†††

Reversibility of FEV₁ (%)

2.2 ± 4.5

1.8 ± 3.8

3.3 ± 5.3

1.0 ± 5.2

Arterial blood gases

PaO₂ (Torr)

90.3 ± 7.5

92.9 ± 5.9

76.6 ± 9.5^***†††

71.9 ± 13.9^***†††

PaCO₂ (Torr)

41.4 ± 3.2

41.7 ± 3.5

40.0 ± 4.0

44.6 ± 7.1^‡

mMRC dyspnea scale

0.0 ± 0.0

0.2 ± 0.6

1.0 ± 1.1^***†††

2.1 ± 1.6^{***†††§}

SGRQ

Total score (units)

8.4 ± 8.3

15.7 ± 12.0

32.6 ± 15.9^***††

57.8 ± 20.8^{***†††¶}

Symptom score (units)

19.6 ± 13.4

30.9 ± 18.9

40.8 ± 21.3^**††

66.2 ± 16.7^{***†††¶}

Activity score (units)

6.0 ± 7.1

20.9 ± 17.2

42.9 ± 24.1^***†††

68.2 ± 29.7^{***†††§}

Impact score (units)

6.2 ± 10.0

8.0 ± 9.9

21.3 ± 13.9^**††

52.0 ± 23.2^{***†††¶}

CES-D scale

1.7 ± 2.9

2.5 ± 3.1

8.5 ± 5.2^***†††

24.5 ± 6.0^{***†††¶}

Treatments for COPD^b

LAMA (no; %)

0

0

33 (66.0)

16 (80.0)

LABA (no; %)

0

0

21 (42.0)

10 (50.0)

ICS (no; %)

0

0

15 (30.0)

11 (55.5)

SRT (no; %)

0

0

7 (14.0)

4 (20.0)