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Table 1 Cluster characteristics in training set, k = 5

From: Quantitative CT and COPD: cluster analysis reveals five distinct subtypes with varying exacerbation risks

Characteristic

Cluster 1

Cluster 2

Cluster 3

Cluster 4

Cluster 5

N

242

130

343

113

111

Age

64.00 (56.00, 68.00)

54.00 (49.00, 60.00)

67.00 (62.00, 72.00)

65.00 (58.00, 71.00)

64.00 (59.00, 70.00)

BMI

27.00 (25.00, 30.00)

31.00 (27.00, 35.00)

29.00 (25.00, 33.00)

25.00 (22.00, 29.00)

25.00 (22.00, 27.50)

GENDER % female

48 (20%)

87 (67%)

203 (59%)

57 (50%)

35 (32%)

CAT

7.00 (3.00, 13.00)

15.00 (7.00, 22.00)

12.00 (7.00, 18.00)

16.00 (10.00, 22.00)

17.00 (12.00, 24.00)

BODE index

0.00 (0.00, 0.00)

0.00 (0.00, 1.00)

1.00 (0.00, 2.00)

2.00 (1.00, 4.00)

3.00 (2.00, 5.00)

FEV1/FVC

0.76 (0.69, 0.81)

0.81 (0.74, 0.85)

0.64 (0.56, 0.72)

0.50 (0.41, 0.60)

0.39 (0.34, 0.45)

FEV1% predicted

0.98 (0.89, 1.08)

0.89 (0.76, 0.96) *

0.74 (0.60, 0.86)

0.56 (0.42, 0.72)

0.40 (0.33, 0.51)

FVC% predicted

1.02 (0.93, 1.12)

0.88 (0.80, 0.95)

0.90 (0.80, 0.99)

0.87 (0.74, 0.99)

0.83 (0.72, 0.96)

Insp_LAA950_total

2.19 (1.17, 4.65)

0.36 (0.26, 0.60)

2.13 (0.98, 4.75)

19.16 (13.21, 28.45)

18.81 (11.61, 26.52)

Exp_density StdDev

173.74 (166.82, 181.98)

173.48 (166.00, 184.30)

169.18 (162.88, 178.78)

184.23 (172.87, 196.72)

163.24 (153.40, 172.22)

Exp_skewness

1.90 (1.66, 2.16)

1.61 (1.37, 1.86)

2.10 (1.85, 2.40)

2.11 (1.62, 2.38)

2.62 (2.37, 2.92)

Exp_kurtosis

3.53 (2.02, 5.39)

2.43 (1.12, 3.88)

4.52 (2.95, 6.11)

3.95 (2.03, 6.26)

7.46 (5.22, 10.04)

Exp_LAA856_TLU

7.10 (2.44, 15.53)

1.42 (0.42, 5.40)

11.92 (5.05, 26.22)

57.35 (36.29, 70.04)

50.92 (38.98, 63.43)

Exp_LAA856_TLL

6.26 (2.62, 14.95)

1.49 (0.41, 3.60)

9.55 (4.22, 21.58)

18.19 (6.39, 29.06)

55.29 (43.78, 65.93)

Exp_LAA856_TRU

6.03 (1.83, 13.96)

1.19 (0.33, 4.69)

10.48 (3.80, 27.27)

64.90 (47.74, 76.56)

48.31 (33.34, 60.02) *

Exp_LAA856_TRL

10.42 (4.50, 19.29)

2.81 (1.10, 5.30)

16.30 (6.80, 27.33)

28.96 (15.32, 41.83)

58.67 (49.20, 68.65)

Wall area†

39.36 (36.15, 43.29) *

32.99 (29.58, 37.14)

31.52 (28.45, 35.45)

32.71 (29.55, 37.46)

33.02 (29.81, 36.69)

Wall area percent†

0.58 (0.56, 0.59)

0.60 (0.58, 0.62)

0.61 (0.60, 0.63)

0.60 (0.58, 0.62)

0.61 (0.59, 0.63)

Lumen area†

30.01 (26.36, 33.67) *

22.77 (19.21, 26.71)

21.01 (18.37, 23.76)

23.82 (19.85, 28.11)

22.06 (18.71, 26.03)

Total bronchial area†

69.35 (62.78, 76.43) *

56.22 (48.83, 63.69)

52.71 (47.95, 58.82)

56.89 (50.55, 65.48)

55.29 (48.20, 61.69)

  1. Notes: values are median (IQR) unless otherwise noted
  2. *: p Value comparing mean in training to validation < 0.05 for Wilcoxon rank sum tests
  3. †: Each subject’s value is replaced by the mean value for 19 bronchi of lung segments
  4. Abbreviations: exp, expiratory; insp, inspiratory; wall area = total bronchial area - lumen area; wall area percent = wall area / total bronchial area; TLU, upper left third of the lung; TLL, lower left third of the lung; TRU, upper right third of the lung; TRL, lower right third of the lung; kurtosis, kurtosis of lung density histogram; skewness, skewness of lung density histogram; StdDev, standard deviation of mean lung density; BMI, body mass index; HU, Hounsfield units
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