Baseline characteristics of the cohort
| Entire cohort | Cases (Home NIV) | Controls (No home NIV) | P value | |
| N | 638 | 585 | 53 | |
| Age (years) | 78 (68, 85) | 78 (68, 85) | 76 (65,83) | 0.25 |
| Male sex | 353 (55%) | 314 (53%) | 39 (73%) | <0.01 |
| Charlson score | 1 (1, 2) | 1 (1,2) | 1 (1,2) | 0.52 |
| Duration of admission (days) | 13 (8, 20) | 13 (9, 20) | 9.5 (6,17) | 0.02 |
| Mean pCO2 (mm Hg) throughout admission | 64 (57, 72) | 64 (58, 72) | 59 (52, 68) | 0.005 |
| Mean bicarbonate (mmol/L) throughout admission | 34 (30, 37) | 33 (30, 36) | 31 (28, 35) | 0.04 |
| Discharge pCO2 (mm Hg) | 65 (55, 77) | 66 (56, 77) | 63 (51, 76) | 0.09 |
| Discharge bicarbonate (mmol/L) | 32 (28, 35) | 32 (28,35) | 30 (25, 35) | 0.002 |
| Cardiac failure | 151 (24%) | 142 (24%) | 9 (17%) | 0.30 |
| Dementia | 7 (1%) | 6 (1%) | 1 (2%) | 0.45 |
| Chronic pulmonary disease | 383 (60%) | 353 (60%) | 30 (56%) | 0.69 |
| Obesity | 64 (10%) | 60 (10%) | 4 (8%) | 0.64 |
| Obstructive sleep apnoea | 33 (5%) | 30 (5%) | 3 (6%) | 0.75 |
| Sedative drugs | 178 (28%) | 165 (28%) | 13 (25%) | 0.63 |
Data are shown as median (IQR) or as counts (percentage) as appropriate for the type of data. P values were calculated by the Wilcoxon test for continuous data and by χ2/Fisher for categorical data, with comparison between the two outcome groups—home NIV or no home NIV.
NIV, non-invasive ventilation.