Characteristics and outcomes of study population
| Mean (SD) age (years) | 67.5 (7.38) |
| M:F ratio | 492:480 |
| Arterial gas tension on admission (median, 5th and 95th centiles) | |
| pH | 7.410 (7.25, 7.506) |
| Paco 2 | 5.96 (4.00, 10.19) |
| Pao 2 | 9.10 (5.30, 18.21) |
| ICU use and outcomes | |
| ICU use | |
| Including A&E intubations | 22/983 (2.2%, 95% CI 1.3 to 3.2) |
| Excluding A&E intubations | 11/972 (1.1%, 95% CI 0.5 to 1.8) |
| Mortality of ICU users | |
| Including A&E intubations | 4/11 died in ICU, 5/11 died during admission |
| Excluding A&E intubations | 2/11 dies in ICU, 5/11 died during admission |
| Median length of stay in ICU (days) | 1 (range 0–4) |
| Outcomes | |
| In hospital mortality | |
| Whole group | 77/972 (7.9%, 95% CI 6.2 to 9.6) |
| Non-acidotic subgroup | 53/773 (6.9%, 95% CI 5.1 to 8.6) |
| Acidotic subgroup | 24/199 (12.1%, 95% CI 7.5 to 16.6) |
| Persistently acidotic subgroup | 22/159 (13.8%, 95% CI 8.5 to 19.2) |
| Median length of stay (5th, 95th centiles) | 8 days (2, 35 days, range 0–95) |