ground ambulance N = 5253 | helicopter N = 3524 | P value | |
---|---|---|---|
Number of death | 387 | 195 | |
Observed mortality, % | 7.4 (6.7–8.1) | 5.5 (4.8–6.3) | |
Expected mortality, % | 8.3 (7.8–8.8) | 8.2 (7.6–8.8) | |
W | + 1.1 (0.6–1.7) | + 2.7 (2.1–3.2) | <0.001 |
Z | 4.0 | 7.7 | |
M | 0.87 | 0.87 | |
SMR | 0.87 (0.80–0.93) | 0.67 (0.60–0.74) | <0.001 |