Table 1 Characteristics of COPDGene participants with COPD, by GDF-15 tertiles

 Age (mean, s.d.)

63.6 (8.4)

59.7 (7.4)

64.6 (8.1)

66.4 (8.3)

<0.001

 Females (%)

47.1

49.4

52.6

39.4

0.01

 African American (%)

16.3

21.7

13.8

13.4

0.02

 BMI (mean, s.d.)

27.3 (6.0)

27.5 (6.0)

26.8 (5.7)

27.6 (6.2)

0.31

 FEV₁ in L (mean, s.d.)

1.25 (0.64)

1.28 (0.69)

1.20 (0.61)

1.26 (0.60)

0.30

 FEV₁ % predicted (mean, s.d.)

43.5 (18.8)

42.9 (19.3)

42.9 (18.6)

44.7 (18.4)

0.50

 FEV₁/FVC % (mean, s.d.)

44.4 (13.6)

44.2 (13.8)

43.9 (13.5)

45.4 (13.6)

0.45

 II

34.1

31.6

33.2

37.7

 III

33.6

32.9

35.8

32.0

 IV

32.3

35.5

31.0

30.3

0.55

 mMRC dyspnea score (mean, s.d.)

2.3 (1.4)

2.3 (1.4)

2.2 (1.4)

2.3 (1.4)

0.48

 Pack-years smoked (mean, s.d.)

52.2 (25.3)

47.8 (23.6)

52.0 (24.2)

56.8 (27.3)

<0.001

 Six-minute walking distance, in f. (mean, s.d.)

1163 (395)

1221 (395)

1180 (377)

1087 (403)

0.001

 Chronic bronchitis (%)

27.0

26.4

26.7

27.7

0.94

 Emphysema % (mean, s.d.)

17.1 (14.4)

18.2 (14.7)

17.1 (14.2)

16.0 (14.2)

0.26

 Pi10 (mean, s.d.)

3.73 (0.14)

3.72 (0.14)

3.71 (0.13)

3.75 (0.14)

0.04

 BMI ≥30

29.0

28.1

26.3

32.5

0.32

 Diabetes

8.7

2.6

4.7

18.6

<0.001

 Currently smoking

29.8

31.6

25.0

32.9

0.13

 Hypertension

43.8

34.6

46.1

50.7

0.002

 Hyperlipidemia

36.6

28.1

41.0

40.7

0.005

 Low (<10%)

44.5

56.3

47.0

30.3

 Intermediate (10%–20%)

39.9

37.7

38.8

43.3

 High (>20%)

15.6

6.1

14.2

26.4

<0.001

 GERD

28.4

30.3

28.0

26.8

0.70

 Asthma

22.5

26.4

22.8

18.2

0.10

 Osteoporosis

15.9

13.4

17.2

16.9

0.46

 Osteoarthritis

15.0

13.0

13.8

18.2

0.24

 Stomach ulcers

8.4

10.4

8.2

6.5

0.31