| Controls | COPD | p-value | ||||
| GOLD I | GOLD II | GOLD III | GOLD IV | |||
| Subjects n | 40 | 38 | 45 | 41 | 37 | |
| Age yrs | 65±8 | 67±9 | 67±9 | 67±9 | 63±8 | 0.17 |
| Males/females n | 20/20 | 19/19 | 22/23 | 22/19 | 25/12 | 0.45 |
| BMI kg·m−2 | 25.9±3.6 | 26.5±4.8 | 26.6±5.9 | 25.2±4.5 | 22.4±3.8 | 0.0006 |
| FFMI kg·m−2 | 17.8±2.1 | 17.9±2 | 17.7±2.7 | 17.6±2.2 | 16.2±1.9 | 0.004 |
| Smoking pack-yrs | 9.1±14.3 | 28.1±22.2 | 42±29.2 | 50±26.2 | 55.5±29.3 | <0.0001 |
| Current smokers % | 11 | 29 | 27 | 14 | 0.09 | |
| Outpatients# % | 47 | 60 | 66 | 89 | 0.001 | |
| Long-acting β-agonist % | 58 | 80 | 85 | 100 | <0.0001 | |
| Long-acting anticholinergic % | 42 | 71 | 83 | 97 | <0.0001 | |
| Inhaled corticosteroid % | 58 | 78 | 83 | 100 | <0.0001 | |
| Oral corticosteroid ≥5 mg·day−1 % | 0 | 0 | 0 | 8 | 0.02 | |
| FEV1 % pred | 103.1±11.7 | 90.8±8.8 | 63.2±8.8 | 39.4±5.5 | 24±3.8 | <0.0001 |
| TL,CO % pred | 89.3±17.1 | 67.5±17.8 | 58.1±14.7 | 39.9±13.9 | 26.6±9 | <0.0001 |
| RV/TLC % | 34±4.6 | 40.6±6.6 | 46.6±8 | 57.9±7.5 | 64.7±6.9 | <0.0001 |
| IC L | 2.8±0.7 | 2.7±0.8 | 2.3±0.8 | 1.9±0.6 | 1.8±0.4 | <0.0001 |
| Pa,O2 kPa | 11.2±1.1 | 10.6±1.5 | 10.2±1.2 | 9.1±1.2 | 9.1±1.3 | <0.0001 |
| Pa,CO2kPa | 5±0.6 | 4.7±0.5 | 5±0.4 | 5.1±0.5 | 5.4±0.6 | <0.0001 |
| MRC score¶ | 1.1±0.3 | 1.8±0.4 | 2.5±0.9 | 3.1±0.9 | 3.6±0.9 | <0.0001 |
| SGRQ | ||||||
| Symptoms | 29.4±24.8 | 49.6±22.8 | 50±23.7 | 61.6±19.1 | <0.0001 | |
| Activity | 34.7±25 | 58.1±23.9 | 70.1±19.4 | 84.5±11.5 | <0.0001 | |
| Impacts | 15.5±15.1 | 29.9±17.4 | 33.8±17.4 | 48.4±18.1 | <0.0001 | |
| Total | 23.1±16.8 | 41.1±17.9 | 47.6±16.4 | 61.5±13.8 | <0.0001 | |
Data are presented as mean±sd, unless otherwise stated. GOLD: Global Initiative for Chronic Obstructive Lung Disease; BMI: body mass index; FFMI: fat-free mass index; FEV1: forced expiratory volume in 1 s; % pred: % predicted; TL,CO: transfer factor of the lung for carbon monoxide; RV: residual volume; TLC: total lung capacity; IC: inspiratory capacity; Pa,O2: arterial oxygen tension; Pa,CO2: arterial carbon dioxide tension; MRC: Medical Research Council; SGRQ: St George’s Respiratory Questionnaire. #: any previous hospital clinic attendance; ¶: on a scale of 1–5.