Lung function at presentation and after 1 year of noninvasive ventilation (NIV)
| At presentation | After 1 year of NIV | p-value | |
| Seated VC (L) | 1.7±1.2 | 2.1±0.9 | <0.001 |
| Seated VC (% pred) | 49±0.17 | 60±0.2 | <0.001 |
| Supine VC (L) | 1.1±0.9 | 1.8±1 | <0.001 |
| Fall in VC seated to supine (% seated) | 42±0.16 | 29±0.17 | <0.001 |
| MEP (cmH20) | 103±8 | 132±7 | 0.14 |
| MEP (% pred) | 84±4 | 96±6 | 0.19 |
| MIP (cmH20) | 34±10 | 50±8 | 0.27 |
| MIP (% pred) | 32±5 | 63±5 | 0.31 |
| SNIP (cmH20) | 29±5 | 47.5±7 | <0.001 |
| SNIP (% pred) | 28±3 | 42±2 | <0.001 |
| MEP/MIP ratio | 3±1.2 | 2.6±1.4 | <0.001 |
| MEP/SNIP ratio | 3.5±1.9 | 2.9±1.7 | <0.001 |
Data are presented as mean±sd, unless otherwise stated. VC: vital capacity; MEP: maximal expiratory pressure; MIP: maximal inspiratory pressure; SNIP: sniff nasal inspiratory pressure.