Clinical characteristics of study populations
| All subjects | Repeatability cohort | |
| Subjects n | 84 | 20 |
| Gender male:female | 62:22 | 15:5 |
| Age years | 70±7.3 | 69±7 |
| FEV1 % predicted | 51±17 | 50±15 |
| FEV1 L | 1.36±0.53 | 1.35±0.43 |
| FVC L | 2.70±0.86 | 2.57±0.55 |
| FEV1/FVC ratio | 0.49±0.13 | 0.52±0.13 |
| GOLD spirometry stage | GOLD 1: 2 | GOLD 1: 0 |
| GOLD 2–3: 69 | GOLD 2–3: 17 | |
| GOLD 4: 13 | GOLD 4:3 | |
| CAT score | 18.64±7.48 | 21.14±7.15 |
| mMRC score | 2.85±0.83 | 2.93±0.75 |
| BMI kg·m−2 | 29±7 | 29±7 |
| Smoker current:ex | 9:75 | 1:19 |
Baseline characteristics presented as mean±sd unless otherwise stated. n=20. FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; GOLD: Global Initiative for Chronic Obstructive Lung Disease; CAT score: COPD Assessment Test score; mMRC: Modified Medical Research Council Dyspnoea Score; BMI: body mass index.