Sociodemographic and clinical characteristics of the cohort at the time of each assessment
| Baseline | 1 year | 2 years | p-value# | ||
| Patients | 543 | 480 (88%) | 428 (79%) | ||
| SGRQ score | |||||
| Symptoms | 44.5±22.2 | 42.5±22.4 | 43.1±23.5 | 0.363 | |
| Activity | 48.7±24.9 | 45.9±25.0 | 46.6±25.0 | 0.111 | |
| Impacts | 32.0±20.9 | 30.4±21.1 | 30.1±20.4 | 0.243 | |
| Total | 39.2±20.1 | 37.1±20.5 | 37.2±20.4 | 0.188 | |
| Sex | |||||
| Male | 522 (96.1%) | 459 (95.6%) | 408 (95.3%) | 0.820 | |
| Female | 21 (3.9%) | 21 (4.4%) | 20 (4.7%) | ||
| Age, years | 68.3±8.3 | 67.6±8.4 | 67.4±8.3 | 0.042 | |
| Body mass index, kg·m−2 | 28.3±4.4 | 28.3±5.2 | 28.1±4.4 | 0.659 | |
| mMRC dyspnoea score | |||||
| 0 | 69 (12.7%) | 85 (17.7%) | 75 (17.5%) | 0.005 | |
| 1 | 264 (48.6%) | 248 (51.7%) | 188 (43.9%) | ||
| 2 | 166 (30.6%) | 127 (26.5%) | 142 (33.2%) | ||
| 3–4 | 44 (8.1%) | 20 (4.3%) | 23 (5.4%) | ||
| FEV1, mL | 1464±441 | 1470±501 | 1513±470 | 0.304 | |
| FEV1, % predicted | 55.0±13.3 | 55.2±16.0 | 57.7±14.7 | 0.027 | |
| <30% predicted | 18 (3.3%) | 22 (4.6%) | 13 (3.0%) | 0.253 | |
| 30–50% predicted | 167 (30.8%) | 131 (27.3%) | 111 (25.9%) | ||
| ≥50% predicted | 358 (65.9%) | 327 (68.1%) | 304 (71.0%) | ||
| Smoking history | |||||
| Exposure, pack-years | 46.8±27.3 | 46.3±26.4 | 46.5±26.0 | 0.989 | |
| Smokers | 114 (23.0%) | 91 (19.0%) | 79 (18.5%) | 0.622 | |
| Former smokers | 414 (76.2%) | 375 (78.1%) | 338 (79.0%) | ||
| Never-smokers | 15 (2.8%) | 14 (2.9%) | 11 (2.6%) | ||
| 6MWD, m | 409±92 | 421±118 | 412±116 | 0.002 | |
| Charlson comorbidity index score | 2.41±1.42 | 2.46±1.42 | 2.47±1.41 | 0.630 | |
| <2 | 172 (31.7%) | 145 (30.2%) | 130 (30.4%) | 0.765 | |
| 2–3 | 264 (48.6%) | 233 (48.5%) | 208 (48.6%) | ||
| >3 | 107 (19.7%) | 102 (21.3%) | 90 (21.0%) | ||
| Previous hospitalisations | |||||
| 0 | 427 (78.6%) | 406 (84.6%) | 377 (88.1%) | 0.033 | |
| 1 | 80 (14.7%) | 51 (10.6%) | 30 (7.0%) | ||
| 2 | 16 (3.0%) | 14 (2.9%) | 16 (3.7%) | ||
| 3 | 9 (1.7%) | 6 (1.3%) | 4 (0.9%) | ||
| >3 | 11 (2.0%) | 3 (0.6%) | 1 (0.2%) | ||
| Treatment¶ | |||||
| 0–1 | 73 (13.4%) | 57 (11.9%) | 48 (11.2%) | 0.204 | |
| 2 | 121 (22.2%) | 91 (19.0%) | 87 (20.3%) | ||
| 3 | 349 (64.3%) | 330 (68.8%) | 293 (68.5%) | ||
| COPD group | |||||
| A | 284 (56.0%) | 260 (62.4%) | 205 (56.9%) | 0.206 | |
| B | 143 (28.2%) | 89 (21.3%) | 90 (25.0%) | ||
| C | 35 (6.9%) | 39 (9.3%) | 33 (9.2%) | ||
| D | 45 (8.9%) | 29 (7.0%) | 32 (8.9%) | ||
| Comorbidities | |||||
| Coronary artery disease | 32 (5.9%) | 27 (5.6%) | 23 (5.4%) | 0.941 | |
| Angina | 40 (7.4%) | 34 (7.1%) | 33 (7.7%) | 0.937 | |
| Congestive heart failure | 79 (14.6%) | 73 (15.2%) | 64 (15.0%) | 0.956 | |
| Arrhythmia | 73 (13.4%) | 68 (14.2%) | 61 (14.3%) | 0.920 | |
| Hypertension | 211 (38.9%) | 200 (41.7%) | 179 (41.8%) | 0.557 | |
| Peripheral artery disease | 49 (9.0%) | 45 (9.4%) | 38 (8.9%) | 0.964 | |
| Cerebrovascular accident | 39 (7.2%) | 40 (8.3%) | 40 (9.4%) | 0.472 | |
| Diabetes | 88 (16.2%) | 85 (17.7%) | 79 (18.5%) | 0.637 |
Data are presented as mean±sd or n (%), unless otherwise stated. SGRQ: St George's Respiratory Questionnaire; mMRC: modified Medical Research Council; FEV1: forced expiratory volume in 1 s; 6MWD: 6-min walking distance. #: significant difference of probability distribution at the three time points calculated for each variable using nonparametric Kruskal–Wallis test; ¶: classified as 0–1 long-acting β2-agonist (LABA) or long-acting muscarinic antagonist (LAMA), 2 out of LABA, LAMA and inhaled corticosteroid (ICS), or all 3 of them (LABA+LAMA+ICS).