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Table 3 Baseline characteristics of subjects in long-term longitudinal data

From: Fractal analysis of low attenuation clusters on computed tomography in chronic obstructive pulmonary disease

 

Current smoker

Former smoker

p-Value

No. of subjects

17

42

 

Follow-up period

6.2 ± 0.6

6.4 ± 0.7

0.22

Age

68 ± 6

67 ± 8

0.70

Sex (male: female)

17:0

42:0

 

Body mass index

21 ± 3

22 ± 3

0.15

Pack-year

64 ± 31

62 ± 32

0.84

Pulmonary function

 FEV1 (% predicted)

61 ± 17

62 ± 19

0.81

 TLC

5.7 ± 0.9

6.0 ± 0.9

0.27

 RV/TLC (%)

43 ± 8

42 ± 8

0.46

 DLCO (% predicted)

56 ± 4

59 ± 3

0.55

 DLCO/VA

3.0 ± 1

3.0 ± 1

0.97

CT

 LAA% (%)

24 ± 6

29 ± 8

0.04

 D950

1.30 ± 0.08

1.25 ± 0.10

0.06

 D’15

1.36 ± 0.13

1.36 ± 0.13

0.88

 D’25

1.27 ± 0.02

1.23 ± 0.08

0.05

 D’35

1.26 ± 0.04

1.23 ± 0.07

0.07

 CT-TLV (L)

5.1 ± 0.9

5.4 ± 0.8

0.24

 Proxy for inspiration

0.89 ± 0.07

0.91 ± 0.13

0.60

  1. FEV1 Forced expiratory volume in 1 s, RV/TLC Residual volume / total lung capacity, DLCO Diffusion capacity, VA Alveolar ventilation. LAA% percent low attenuation area (LAA). D950, D’15, D’25, and D’35 are exponents that characterize a power law that governs the cumulative frequency size distribution of LAA clusters that are identified using a threshold of − 950 HU and the 15th, 25th, and 35th percentiles of a CT density histogram, respectively. A proxy for inspiration indicates the degree of the inspiration level during a CT scan that was obtained by dividing the total lung volume measured on CT (CT-TLV) by physiologically measured TLC
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BMC Pulmonary Medicine

ISSN: 1471-2466

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