Comparison of demographic and clinical characteristics in COPD Cohorts Collaborative International Assessment (3CIA) COPD patients included/excluded in this analysis
| Excluded | Included | p-value | |
| Subjects n | 8316 | 8823 | |
| Age years | 64.2±10.7 | 63.9±9.8 | 0.08 |
| Male sex | 6232 (74.9%) | 5552 (62.9%) | <0.001 |
| BMI kg·m-2 | 26.5±4.9 | 27.0±5.8 | <0.001 |
| Modified MRC dyspnoea scale | 1.5±1.3 | 1.8±1.4 | <0.001 |
| 0 | 1647 (23.4%) | 1957 (22.2%) | <0.001 |
| 1 | 2261(32.1%) | 1886 (21.4%) | |
| 2 | 1641 (23.3%) | 1772 (20.1%) | |
| 3 | 688 (9.8%) | 1951 (22.1%) | |
| 4 | 805 (11.4%) | 1257 (14.3%) | |
| Six-min walk distance m | 415.4±108.8 | 376.9±129.1 | <0.001 |
| FEV1 post BD mL | 1.7±0.7 | 1.6±0.8 | <0.001 |
| FEV1 post BD % | 60.8±22.1 | 54.8±22.3 | <0.001 |
| Smoker | <0.001 | ||
| Former | 3989 (49.1%) | 5392 (61.4%) | |
| Current | 3589 (44.2%) | 3174 (36.1%) | |
| Never | 542 (6.7%) | 222 (2.5%) | |
| Pack-years | 46.4±28.8 | 42.1±28.3 | <0.001 |
| Cough | 1103 (54.2%) | 342 (43.9%) | <0.001 |
| Sputum | 1159 (42.1%) | 341 (43.9%) | 0.353 |
| Diabetes | 354 (6.7%) | 303(16.6%) | <0.001 |
| Cardiac disease | 1072 (30.8%) | 467 (25.9%) | <0.001 |
| Chronic bronchitis | 166 (38.7%) | 787 (69.5%) | <0.001 |
| Hypertension | 454 (40.4%) | 826 (44.8%) | 0.028 |
| Asthma | 1243 (26.1%) | 209 (10.7%) | <0.001 |
| Spirometry staging | <0.001 | ||
| 1 | 1567 (19%) | 1153 (13.1%) | |
| 2 | 3892 (47.1%) | 3711 (42.1%) | |
| 3 | 2126 (25.8%) | 2654 (30.1%) | |
| 4 | 671 (8.1%) | 1301 (14.8%) | |
| Long-term oxygen therapy | 119 (1.4%) | 430 (4.8%) | 0.259 |
Data are presented as n (%), mean±sd or median (interquartile range), unless otherwise stated. BMI: Body mass index; MRC: Medical Research Council; FEV1: forced expiratory volume in 1 s; BD: bronchodilator.