Baseline characteristics of the patients
| Characteristics | Total | Missing data, n (%) |
| Number of patients | 10 141 | |
| Age, year | 69.0 (57.0–78.0) | 0 (0) |
| Age category, n (%) | ||
| 16–39 | 786 (7.8) | 0 (0) |
| 40–79 | 7434 (73.3) | 0 (0) |
| ≥80 | 1921 (18.9) | 0 (0) |
| Male, n (%) | 6040 (59.6) | 0 (0) |
| Physiological variables | ||
| Systolic blood pressure, mm Hg | 130 (110–150) | 0 (0) |
| Heart rate, beats/min | 90 (78–108) | 0 (0) |
| Breath rate, breaths/min | 20 (20–22) | 4 (0.0) |
| Body temperature, °C | 36.7 (36.4–37.2) | 10 (0.1) |
| SaO2, % | 96 (93–98) | 230 (2.3) |
| Consciousness (alert), n (%) | 9076 (89.5) | 0 (0) |
| Supplemental oxygen, n (%) | 4012 (39.6) | 0 (0) |
| NEWS | 4 (1–7) | 236 (2.3) |
| Initial laboratory results | ||
| Platelet, ×103/mm3 | 220 (162–287) | 56 (0.6) |
| Creatinine, mg/dL | 0.87 (0.66–1.31) | 61 (0.6) |
| Bilirubin, mg/dL | 0.68 (0.43–1.10) | 80 (0.8) |
| PO2, mm Hg | 76 (59–96) | 371 (3.7) |
| Hyperoxaemia variables results | ||
| PaO2MAX | 99.0 (83.0–126.0) | 0 (0) |
| PaO2AVG | 81.0 (68.9–99.0) | 0 (0) |
| PaO2MED | 80.0 (67.5–97.5) | 0 (0) |
| AUC72 | 63.8 (23.2–153.2) | 0 (0) |
| Mortality, n (%) | 584 (5.8) | 0 (0) |
AUC72, area under the curve divided by elapsed time between ED arrival and the last result of PO2 within 72 hours; NEWS, National Early Warning Score; PaO2AVG, average value of PO2 within 72 hours; PaO2Max, highest value of PO2 within 72 hours; PaO2MED, median value of PO2within 72 hours; PO2, PaO2of oxygen; SaO2, oxyhaemoglobin saturation.
Data are medians (IQR) unless otherwise stated.