Table 1 Comparisons of baseline characteristics of the included participants with the excluded participants

Number of patients

292

425

-

  Age (year), mean (SD)

67.3 (8.58)

67.9 (9.5)

0.3564

  Male, n (%)

214 (73.29 %)

268 (63 %)

0.005

Race, n (%)

  New Zealand European

287 (98.29 %)

414 (97.6 %)

0.637

  Maori/Pacific Islander

3 (1.03 %)

6 (1.4 %)

  Other

2 (0.68 %)

4 (1 %)

  Height (cm), mean (SD)

169.8 (8.6)

168 (8.8)

0.018

  Weight (kg), mean (SD)

72.6 (16.5)

72.6 (16)

0.993

Smoking history, n (%)

  Current smoker

71 (24.32 %)

116 (28 %)

0.272

  Ex-smoker

221 (75.68 %)

298 (72 %)

  Average tobacco consumption (pack year), mean (SD)

56.58 (33.3)

53.7 (30)

0.355

  Number of previous exacerbations within 2 years, mean (SD)

5.11 (2.4)

4.15 (2.5)

<0.0001

Spirometry

  FEV₁ (l), mean (SD)

0.935 (0.43)

1.17 (0.67)

0.0001

  FEV₁ (% predicted), mean (SD)

34 (14.8)

43.5 (23)

<0.0001

  FVC (l), mean (SD)

2.23 (0.83)

2.28 (0.93)

0.7983

  FEV₁/FVC mean (SD)

42 (10.2)

50 (14.8)

<0.0001