Mortality (%) according to baseline characteristics, with identification of subgroups with a statistically significant improved survival with continuous long-term oxygen therapy (LTOT) compared with nocturnal oxygen only (Nocturnal Oxygen Treatment Trial [30])
| Variable of interest | Continuous LTOT (%) | Nocturnal oxygen (%) |
| PaCO2 ≥43 mmHg (5.7 kPa) | 19.6 | 46.0 |
| pH <7.40 | 16.0 | 42.2 |
| FVC <1.89 L | 20.8 | 43.5 |
| Mean room air SaO2 during sleep <85% | 24.4 | 50.0 |
| Haematocrit <47.4% | 21.7 | 41.5 |
| Mean PAP <27 mmHg | 17.5 | 37.0 |
| Pulmonary vascular resistance <279 dynes·s·cm−5 | 12.8 | 33.3 |
FVC: forced vital capacity; PaCO2: arterial carbon dioxide tension; PAP: pulmonary artery pressure; SaO2: arterial oxygen saturation.