Table 1 Participant characteristics

Subjects (n)

42

105

Age (years, mean (SD))

66.8 (10.2)

59.4 (11.8)

 < 0.001

Sex, Male (n (%))

21 (50%)

50 (48%)

0.9

Body mass index (kg/m², mean (SD))

34.6 (11.0)

29.6 (6.1)

 < 0.001

Smoking exposure

 Ever smoked (n (%))

36 (86%)

54 (52%)

 < 0.001

 Pack years (median (IQR))

45 (22.5 – 67.5)

22.5 (2.5 – 43.8)

0.04

Highest level of educational attainment (n (%))

0.02

 Below upper secondary

23 (55%)

35 (33%)

 Upper secondary, post-secondary non-tertiary or tertiary

19 (45%)

70 (67%)

Household income range^a (n (%))

 < 0.001

 Lowest quartile

1 (2%)

0 (0%)

 Medium lowest quartile

36 (86%)

54 (51%)

 Medium highest quartile

2 (5%)

23 (22%)

 Highest quartile

0 (0%)

22 (21%)

 No response

3 (7%)

6 (6%)

Self-reported past medical history (n (%))

 Asthma

19 (45%)

26 (24%)

0.02

 Chronic obstructive pulmonary disease

22 (52%)

16 (15%)

 < 0.001

 Pulmonary fibrosis

3 (7%)

1 (1%)

0.07

 Bronchiectasis

1 (2%)

2 (2%)

1

 Obstructive sleep apnea

18 (43%)

13 (12%)

 < 0.001

 Atrial fibrillation

11 (26%)

6 (6%)

0.001

 Coronary artery disease

11 (26%)

8 (8%)

0.005

 Congestive cardiac failure

14 (33%)

2 (2%)

 < 0.001

 Cerebrovascular accident

8 (19%)

4 (4%)

0.005

 Peripheral vascular disease

4 (10%)

1 (1%)

0.06

 Chronic kidney disease

7 (17%)

9 (9%)

0.2

 Chronic liver disease

4 (10%)

1 (1%)

0.02

 Hypertension

27 (64%)

37 (35%)

0.002

 Diabetes mellitus

17 (40%)

18 (17%)

0.005

 Solid organ malignancy

5 (12%)

6 (6%)

0.3

 Depression, anxiety or other chronic mental health disorder

18 (43%)

20 (19%)

0.006

Charlson Comorbidity Index (median (IQR))

2 (1 – 5)

1 (0 – 1)

 < 0.001