Table 1 Baseline characteristics of patients with COPD classified in terms of the presence of resting hyperinflation and emphysema.

From: Resting hyperinflation and emphysema on the clinical course of COPD

Characteristics

Group 1 (n = 61)

Group 2 (n = 124)

Group 3 (n = 20)

Group 4 (n = 105)

P-value*

Age

65.9 ± 7.9

66.1 ± 7.1

68.3 ± 7.6

66.8 ± 7.4

0.581

Men, n (%)

59 (96.7)

120 (96.8)

19 (95.0)

103 (98.1)

0.859

Body mass index, kg/m2

24.3 ± 3.1

22.9 ± 2.7

24.0 ± 3.4

21.6 ± 3.5

<0.001

Smoking status at baseline, n (%)

    

0.469

Current smokers

25 (41.0)

47 (37.9)

6 (30.0)

32 (30.5)

 

Former smokers

36 (59.0)

77 (62.1)

14 (70.0)

73 (69.5)

 

Pack-years of smoking

41.8 ± 21.7

47.8 ± 28.0

48.3 ± 35.4

45.3 ± 24.1

0.492

SGRQ score

32.0 ± 16.7

28.9 ± 16.5

34.2 ± 17.0

42.3 ± 17.6

<0.001

mMRC grade

1.5 ± 1.1

1.4 ± 1.0

1.9 ± 1.2

2.0 ± 1.0

<0.001

Chronic bronchitis, n (%)

21 (34.4)

29 (23.4)

6 (30.0)

29 (27.6)

0.460

Lung function at baseline

FEV1, % predicted

68.4 ± 17.0

66.3 ± 15.3

57.8 ± 13.5

47.0 ± 16.7

<0.001

FEV1, z-score

−2.7 ± 1.4

−3.1 ± 1.2

−3.8 ± 1.1

−4.8 ± 1.2

<0.001

FVC, L

3.6 ± 0.8

3.9 ± 0.7

2.8 ± 0.6

3.1 ± 0.7

<0.001

FEV1/FVC

52.8 ± 9.7

47.2 ± 9.3

52.6 ± 9.1

40.3 ± 9.9

<0.001

DLCO, % predicted

87.9 ± 22.6

75.1 ± 21.5

94.0 ± 27.6

70.1 ± 24.1

<0.001

RV/TLC, %

36.9 ± 8.5

38.5 ± 9.2

58.8 ± 7.6

58.6 ± 7.6

<0.001

CT emphysema index, %

5.1 ± 3.0

25.9 ± 11.5

4.4 ± 3.0

32.5 ± 13.9

<0.001

Bronchodilator reversibility, n (%)

6 (9.8)

13 (10.5)

6 (30.0)

14 (13.3)

0.090

Eosinophil count, /uL

342.7 ± 554.7

257.1 ± 277.5

320.2 ± 266.8

248.6 ± 235.5

0.299

Exacerbation history, n (%)†

9 (14.8)

22 (17.7)

2 (10.0)

28 (26.7)

0.129

Exacerbation history, frequency‡

0.7 ± 2.3

0.6 ± 2.1

0.2 ± 0.6

0.6 ± 1.9

0.821

  1. Group 1: RV/TLC ≤ upper limit of normal (ULN) and emphysema index ≤ 10%, Group 2: RV/TLC ≤ ULN and emphysema index >10%, group 3: RV/TLC > ULN and emphysema index ≤ 10%, group 4: RV/TLC > ULN and emphysema index >10%
  2. SGRQ, St. George Respiratory Questionnaire; mMRC, modified Medical Round Council; FEV1, forced expiratory volume in one second; FVC, forced vital capacity; DLCO, diffusing capacity of carbon monoxide.
  3. *P-values are for the overall comparison of the four groups and are based on analyses of variance and chi-square tests.
  4. †History of ≥ 2 moderate, or ≥1 severe exacerbations in the past year.
  5. ‡The number of moderate or severe exacerbations in the past year.
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