| GOLD 1 | GOLD 2 | GOLD 3 | GOLD 4 | p-value | |
| Subjects | 21 (6.5) | 135 (41.9) | 107 (33.2) | 59 (18.3) | |
| Male/female % | 71.4/28.6 | 78.5/21.5 | 71.0/29.0 | 84.8/15.2 | 0.20 |
| Age yrs | 66.0 (58.0–75.0) | 66.0 (58.0–72.0) | 64.0 (57.0–73.0) | 63.0 (58.0–72.0) | 0.48 |
| Smoking exposure pack-yrs | 41.2 (28.0–56.0) | 42.0 (26.0–55.0) | 38.0 (25.0–50.0) | 43.8 (30.0–72.0) | 0.74 |
| FEV1 % pred | 84.7 (81.9–86.4) | 65.4 (59.1–71.4) | 40.3 (34.4–44.8) | 25.1 (21.2–28.8) | <0.0001 |
| FVC % pred | 109.8 (99.9–115.2) | 87.4 (78.8–96.4) | 74.6 (59.4–86.8) | 57.0 (48.6–70.3) | <0.0001 |
| BMI kg·m−2 | 26.5 (24.1–28.1) | 25.3 (23.0–29.1) | 24.1 (20.4–27.4) | 22.3 (18.3–25.6) | <0.0001 |
| MMRC dyspnoea score | 1.0 (0.0–1.0) | 1.0 (1.0–2.0) | 2.0 (1.0–3.0) | 3.0 (2.0–4.0) | <0.0001 |
| BOD score | 1.0 (1.0–2.0) | 2.0 (1.0–2.0) | 4.0 (3.0–5.0) | 5.0 (4.0–6.0) | <0.0001 |
| SGRQ total score | 27.2 (16.3–56.6) | 36.3 (26.8–52.3) | 50.9 (37.7–61.0) | 63.9 (46.4–72.0) | <0.0001 |
| HAD scale | |||||
| Total score | 15.0 (8.0–19.0) | 13.0 (9.0–17.0) | 13.0 (8.0–18.0) | 14.0 (8.0–21.0) | 0.46 |
| Anxiety score | 8.0 (5.0–11.0) | 7.0 (5.0–10.0) | 7.0 (5.0–10.0) | 8.0 (4.0–11.0) | 0.66 |
| Depression score | 6.0 (3.0–10.0) | 6.0 (3.0–8.0) | 5.0 (3.0–9.0) | 7.0 (3.0–11.0) | 0.33 |
| Exacerbations per patient per yr | 2.0 (0.0–3.0) | 1.0 (0.0–2.0) | 2.0 (1.0–3.0) | 2.0 (1.0–5.0) | <0.0001 |
| Comorbidities % | |||||
| Coronary artery disease | 19.1 | 20.3 | 18.3 | 5.4 | 0.06 |
| Chronic heart failure | 9.5 | 17.7 | 18.3 | 19.3 | 0.49 |
| Diabetes mellitus | 9.5 | 5.1 | 11.5 | 10.9 | 0.95 |
| Hypertension | 47.6 | 44.4 | 35.6 | 23.2 | 0.005 |
| Inhaled therapy % | |||||
| LABA | 52.4 | 56.3 | 73.8 | 84.8 | <0.0001 |
| ICS | 52.4 | 54.8 | 72.9 | 78.0 | <0.0001 |
| Tiotropium | 19.1 | 23.0 | 17.8 | 18.6 | 0.44 |
Data are presented as n (%) or median (interquartile range), unless otherwise stated. FEV1: forced expiratory volume in 1 s; % pred: % predicted; FVC: forced vital capacity; BMI: body mass index; MMRC: modified Medical Research Council; BOD score: BMI, obstruction (FEV1 % pred) and dyspnoea (MMRC scale); SGRQ: St George’s Respiratory Questionnaire; HAD: hospital anxiety and depression; LABA: long-acting β-agonist; ICS: inhaled corticosteroids.