Association between helicopter with physician versus ground emergency medical services and survival of adults with major trauma in Japan

Table 4 Association between transportation method and survival outcome ^a

	Survival OR (95% CI)
Analysis	At discharge	At ED
Crude (N = 24,293)	0.992 (0.895 to 1.098)	1.437 (1.193 to 1.730)
Unconditional logistic regression
Standard (n = 15,382)	1.277 (1.049 to 1.556)	1.141 (0.729 to 1.785)
After propensity score matching^b (n = 2,510)	1.446 (1.220 to 1.714)	2.367 (1.822 to 3.075)
Conditional logistic regression (n = 2,510)	1.230 (1.017 to 1.488)	1.703 (1.255 to 2.311)

^aCI: Confidence interval; ED: Emergency department; OR: Odds ratio. ^bThe covariates used to estimate the propensity score were age, sex, mechanism of injury, type of trauma, initial vital signs (systolic blood pressure, heart rate, risk ratio) and Injury Severity Score.

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