| OSA group | OSA–OHS + OHS group | |
| n = 37 | n = 51 | |
| n (%) | n (%) | |
| Epworth Sleepiness Scale | 14.8±6.3 | 15.9±6.3 |
| Weight (kg) | 125.0±31.4 | 141.0±37.2* |
| BMI (kg.m−2) | 44.9±12.6 | 52.7±14.3* |
| Elevated jugular venous pressure | 15 (40.5) | 26 (50.9) |
| Peripheral oedema | 21 (56.8) | 38 (74.5) |
| FVC (litres) | 2.5±1.3 | 1.8±0.8* |
| FEV1/FVC | 79.6±14.5 | 75.2±12.2 |
| PaCO2 (kPa) | 6.2±1.0 | 7.3±1.2* |
| PaO2 (kPa) | 9.3±2.0 | 7.6±1.3* |
| HCO3− (mmol/l) | 27.5±3.4 | 31.5±3.7* |
| Haematocrit (%) | 43.6±10.4 | 47.3±7.0 |
*p<0.05 for comparison between groups.
BMI, body mass index; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; OHS, obesity hypoventilation syndrome; OSA, obstructive sleep apnoea.