Associations with the obstruction with decreased central drive index
| r-value | p-value | |
| Age | −0.09 | 0.609 |
| BMI | −0.22 | 0.269 |
| Time from ALS onset | −0.08 | 0.673 |
| Time from NIV onset | −0.15 | 0.429 |
| Daily hours of use of NIV | −0.18 | 0.323 |
| V′E with NIV | −0.24 | 0.205 |
| ALSFRS-R | 0.02 | 0.883 |
| NBS | −0.37 | 0.044 |
| FVC | 0.01 | 0.958 |
| FVC % pred | −0.02 | 0.919 |
| PImax | −0.10 | 0.588 |
| PEmax | 0.10 | 0.592 |
| SNIP | 0.13 | 0.948 |
| MIC | −0.05 | 0.779 |
| PCF | −0.03 | 0.857 |
| PCFMIC | −0.13 | 0.504 |
| PCFMI-E | −0.10 | 0.587 |
| Apnoeic threshold | −0.02 | 0.901 |
| CO2R | −0.35 | 0.037 |
| Controller gain | 0.59 | 0.001 |
| Plant gain | −0.23 | 0.222 |
BMI: body mass index; ALS: amyotrophic lateral sclerosis; NIV: noninvasive ventilation; V′E: minute ventilation; ALSFRS-R: Revised Amyotrophic Lateral Sclerosis Functional Rating Scale; NBS: Norris scale bulbar subscore; FVC: forced vital capacity; PImax: maximum inspiratory pressure; PEmax: maximum expiratory pressure; SNIP: sniff nasal inspiratory pressure; MIC: maximum insufflation capacity; PCF: peak cough flow; PCFMIC: manually assisted PCF; PCFMI-E: mechanically assisted PCF; CO2R: carbon dioxide reserve.