Variables | Patients n | All patients | Patients n | Patients with no exacerbations | Patients n | Patients with one or two exacerbations | Patients n | Patients with three or more exacerbations | p-value |
Age years | 1349 | 65.3±8.7 | 267 | 66.0±9.2 | 478 | 65.4±8.6 | 604 | 64.9±8.6 | 0.227 |
Males | 1349 | 682 (50.6%) | 267 | 165 (61.8%) | 478 | 235 (49.2%) | 604 | 282 (46.7%) | <0.001# |
Current smokers | 1272 | 311 (24.4%) | 253 | 59 (23.3%) | 450 | 116 (25.8%) | 569 | 136 (23.9%) | 0.706 |
Smoking history pack-years | 1349 | 41.0±19.0 | 267 | 41.7±19.1 | 478 | 40.3±18.5 | 604 | 41.2±19.3 | 0.582 |
Chronic oxygen therapy | 1326 | 305 (23.0%) | 263 | 32 (12.2%) | 471 | 111 (23.6%) | 592 | 162 (27.4%) | <0.001# |
BMI kg·m−2 | 1331 | 26.4±5.9 | 263 | 27.0±5.9 | 472 | 26.4±5.8 | 596 | 26.2±6.0 | 0.180 |
FFMI kg·m−2 | 1310 | 16.8±2.5 | 262 | 17.4±2.7 | 460 | 16.6±2.3 | 588 | 16.7±2.5 | <0.001# |
FEV1 % predicted | 1349 | 48.0±20.8 | 267 | 60.1±21.6 | 478 | 47.9±20.2 | 604 | 42.9±18.6 | <0.001¶ |
FVC % predicted | 1349 | 94.7±22.2 | 267 | 102.6±21.2 | 478 | 96.1±22.2 | 604 | 90.2±21.5 | <0.001¶ |
FEV1/FVC ratio | 1349 | 37.5±12.9 | 264 | 44.0±14.0 | 478 | 37.1±12.4 | 604 | 34.9±11.9 | <0.001¶ |
ITGV % predicted | 1292 | 147.3±39.3 | 264 | 130.6±36.1 | 461 | 148.4±37.8 | 567 | 154.2±39.6 | <0.001¶ |
TLC % predicted | 1291 | 115.3±19.5 | 264 | 109.9±19.6 | 461 | 115.8±19.0 | 566 | 117.5±19.5 | <0.001# |
RV % predicted | 1291 | 160.2±55.1 | 264 | 135.0±45.6 | 461 | 160.6±52.9 | 566 | 171.7±57.2 | <0.001¶ |
TLCO % predicted | 1247 | 50.0±17.3 | 257 | 55.3±18.3 | 451 | 49.5±16.2 | 539 | 47.9±17.3 | <0.001# |
KCO % predicted | 1247 | 64.9±22.5 | 257 | 69.3±24.1 | 451 | 63.6±21.0 | 539 | 63.9±22.7 | 0.002# |
PaO2 kPa | 1278 | 9.3±1.5 | 261 | 9.6±1.6 | 450 | 9.3±1.5 | 567 | 9.2±1.5 | 0.015# |
PaCO2 kPa | 1279 | 5.4±1.0 | 261 | 5.1±0.7 | 450 | 5.5±0.9 | 568 | 5.6±1.1 | <0.001# |
COTE index | 1289 | 264 | 454 | 571 | 0.733 | ||||
| 1162 (90.1%) | 238 (90.2%) | 413 (91.0%) | 511 (89.5%) | |||||
| 127 (9.9%) | 26 (9.8%) | 41 (9.0%) | 60 (10.5%) | |||||
CAT score | 1270 | 22.0±6.4 | 252 | 19.3±6.6 | 458 | 21.5±6.4 | 560 | 23.7±5.8 | <0.001¶ |
6MWD m | 1326 | 399.0±119.1 | 266 | 450.5±105.2 | 471 | 404.6±110.5 | 589 | 371.3±123.3 | <0.001¶ |
6MWD % predicted | 1317 | 63.5±17.8 | 262 | 64.4±17.9 | 467 | 64.9±17.2 | 588 | 62.1±18.2 | 0.023+ |
mMRC dyspnoea score | 1341 | 266 | 475 | 600 | <0.001¶ | ||||
0 | 18 (1.3%) | 6 (2.3%) | 7 (1.5%) | 5 (0.8%) | |||||
1 | 184 (13.7%) | 69 (25.9%) | 64 (13.5%) | 51 (8.5%) | |||||
2 | 557 (41.5%) | 131 (49.2%) | 215 (45.3%) | 211 (5.2%) | |||||
3 | 326 (24.3%) | 38 (14.3%) | 118 (24.8%) | 170 (8.3%) | |||||
4 | 256 (19.1%) | 22 (8.3%) | 71 (14.9%) | 163 (27.2%) | |||||
Hospitalisations in last year | 1344 | 267 | 476 | 601 | <0.001¶ | ||||
0 | 721 (53.6%) | 254 (95.1%) | 288 (60.5%) | 179 (9.8%) | |||||
1 | 321 (23.9%) | 12 (4.5%) | 143 (30.0%) | 166 (7.6%) | |||||
2 | 146 (10.9%) | 1 (0.4%) | 41 (8.6%) | 104 (7.3%) | |||||
3 | 62 (4.6%) | 0 (0.0%) | 0 (0.0%) | 62 (10.3%) | |||||
≥4 | 94 (7.0%) | 0 (0.0%) | 4 (0.8%) | 90 (15.0%) | |||||
Intensive care in last year | 1339 | 108 (8.1%) | 266 | 7 (2.6%) | 476 | 39 (8.2%) | 597 | 62 (10.4%) | 0.001# |
Data are presented as mean±sd or n (%) unless otherwise stated. BMI: body mass index; FFMI: fat-free mass index; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; ITGV: intrathoracic gas volume; TLC: total lung capacity; RV: residual volume; TLCO: transfer factor of the lungs for carbon monoxide; KCO: transfer coefficient for carbon dioxide; PaO2: arterial oxygen tension; PaCO2: arterial carbon dioxide tension; COTE: COPD-Specific Co-Morbidity Test; CAT: COPD Assessment Test; 6MWD: 6-min walking distance; mMRC: modified Medical Research Council. #: significant difference between patients with no exacerbations and those with one or two exacerbations, and between no exacerbations and three or more exacerbations; ¶: significant difference between all three groups; +: significant difference between patients with one or two exacerbations and those with three or more exacerbations.