| Groups | FEV1 (% pred) | VC (% pred) | FEV1/FVC (%) |
| Neuromuscular disease | 67.4 (19.0) | 65.5 (21.1) | 74.4 (13.3) |
| Dyspnoea of unknown cause | 79.2 (18.6) | 80.1 (27.3) | 78.4 (9.7) |
| COPD | 50.9 (19.7) | 65.7 (21.8) | 58.8 (15.7) |
| Rheumatological disease | 62.4 (20.5) | 65.5 (22.0) | 78.5 (12.9) |
| Chest wall disease | 59.8 (20.5) | 59.8 (20.2) | 78.8 (9.3) |
| Other restrictive lung diseases | 51.3 (21.4) | 54.0 (25.2) | 76.6 (8.1) |
| Obesity hypoventilation | 52.3 (18.3) | 55.7 (13.1) | 78.2 (8.4) |
FEV1, forced expiratory volume in 1 s; VC, vital capacity; FVC, forced vital capacity.