Baseline characteristics of the London patients with COPD and control subjects: data are expressed as mean (SD) or number (%)
| COPD (n=204) | Control (n=65) | p Value | |
| Age (years) | 70.7 (11.1) | 66.9 (6.6) | <0.001 |
| FEV1 (litres) | 1.17 (0.51) | 2.50 (0.77) | |
| FEV1 % predicted | 48.2 (19.9) | 99.4 (18.6) | |
| FVC (litres) | 2.50 (0.93) | 3.22 (1.04) | |
| BMI (kg m−2) | 26.0 (5.5) | 26.3 (3.8) | 0.34 |
| Smoking (pack-years) | 51.6 (38.7) | 17.4 (22.2) | <0.001 |
| SpO2 (breathing air) | 95 (2) | 96 (1) | <0.001 |
| Male | 119 (58%) | 21 (32%) | <0.001 |
| Current smoker | 52 (26%) | 12 (18%) | 0.12 |
| Frequent exacerbator* | 69 (34%) | ||
| GOLD stage 1/2/3/4 (n) | 14/83/73/34 |
↵* ≥3 exacerbations/year, calculated from the diary cards.
BMI, body mass index; COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease.