Population characteristics
| Patients alive at follow-up (n: 69) Mean±SD/median (IQR) | Patients dead at follow-up (n: 51) Mean±SD/median (IQR) | p value | |
| Age (years) | 66.3±10.0 | 72.5±8.9 | <0.001 |
| Male (%) | 26 (51.0%) | 32 (46.4%) | 0.713 |
| Body mass index (kg/m2) | 27.7 (23.3 to 33.6) | 20.9 (18.2 to 27.7) | 0.713 |
| COPD history | |||
| Current smoker (%) | 23 (33.3%) | 24 (41.1%) | 0.136 |
| Smoking history (pack-years) | 40 (20 to 50) | 40 (30 to 56) | 0.213 |
| Use of long-term oxygen therapy (%) | 1 (2.0%) | 12 (17.4%) | 0.007 |
| Exacerbation frequency (/12 months) | 2 (0 to 4) | 4 (1 to 6) | 0.079 |
| Hospital admission frequency (/12 months) | 0 (0 to 1) | 1 (0 to 2) | 0.007 |
| Comorbidities | |||
| Ischaemic heart disease (%) | 14 (27.5%) | 20 (29.0%) | 1 |
| Cerebrovascular disease (%) | 5 (9.8%) | 8 (11.6%) | 1 |
| Hypertension (%) | 25 (49.0%) | 28 (40.6%) | 0.457 |
| Diabetes mellitus (%) | 12 (17.4%) | 8 (11.6%) | 0.091 |
| Admission | |||
| MRC dyspnoea grade at admission | 4 (3 to 5) | 5 (4 to 5) | 0.045 |
| Respiratory rate at admission (/min) | 25 (20 to 29) | 26 (20 to 31) | 0.670 |
| DECAF score at admission | 1 (0 to 1) | 1 (0 to 2) | 0.044 |
| CAT at admission | 30 (26 to 34) | 27 (23 to 31) | 0.022 |
| Admission arterial blood gas | |||
| pH | 7.41 (7.37 to 7.45) | 7.40 (7.35 to 7.42) | 0.029 |
| PaO2 (kPa) | 8.22 (7.46 to 8.91) | 8.37 (7.42 to 9.84) | 0.3756 |
| PaCO2 (kPa) | 5.05 (4.61 to 5.91) | 6.09 (4.96 to 7.24) | 0.002 |
| Bicarbonates (mmol/L) | 24.4 (23.0 to 26.3) | 26 (23/5 to 29.4) | 0.023 |
| At discharge | |||
| CAT | 24 (17 to 28) | 24 (17 to 29) | 0.507 |
| Saint-Georges Respiratory Questionnaire | 65.0 (59.5 to 75.4) | 62.8 (56.8 to 72.2) | 0.275 |
| Hospital Anxiety and Depression Scale | 15.5±7.5 | 15.7±7.7 | 0.775 |
| FEV1 (L) | 0.85 (0.63 to 0.98) | 0.62 (0.46 to 0.85) | <0.001 |
| FVC (L) | 1.62 (1.62 to 2.12) | 1.40 (1.14 to 1.96) | 0.067 |
| Readmission or death within 28 days (%) | 11 (26.6%) | 18 (26.1%) | 0.668 |
| Baseline EMG | |||
| EMG para (µV) | 8.80 (6.46 to 14.7) | 10.88 (7.43 to 17.55) | 0.048 |
| EMG para%max | 15.1 (11.0 to 22.0) | 16.5 (11.2 to 22.2) | 0.446 |
| Respiratory rate (/min) | 21 (17 to 26) | 21 (18 to 24) | 0.885 |
| NRDI (/min) | 313 (221 to 438) | 344 (228 to 456) | 0.403 |
| Discharge EMG | |||
| EMGpara (µV) | 8.17 (5.77 to 10.85) | 11.33 (8.09 to 17.02) | <0.001 |
| EMGpara%max | 12.8 (9.1 to 17.4) | 15.7 (11.8 to 22.6) | 0.008 |
| Respiratory rate (/min) | 20 (18 to 23) | 19 (17 to 22) | 0.120 |
| NRDI (/min) | 228 (151 to 368) | 319 (232 to 458) | 0.004 |
| EMG change from baseline to discharge | |||
| ΔEMGpara (µV) | −0.74 (−5.06 to 0.36) | 0.73 (-3.53 to 2.48) | 0.016 |
| ΔEMGpara%max | −1.96 (−7.61 to 0.79) | −0.95 (−4.44 to 3.24) | 0.054 |
| ΔRespiratory rate (/min) | −2 (−4 to 1) | −1 (−3 to 3) | 0.043 |
| ΔNRDI (/min) | −61(−173 to 8) | −9 (−112 to 73) | 0.039 |
Δ, change in; CAT, COPD assessment tool; DECAF, dyspnea, eosinopenia, consolidation, acidemia, fibrillation; EMG, electromyography; MRC, medical research council; NRDI, neural respiratory drive index.