The prognostic value of blood lactate levels relative to that of vital signs in the pre-hospital setting: a pilot study

Table 3 Multivariable Cox proportional hazards model for the identification of independent variables associated with in-hospital death

Variable	Start model			Final model
	HR	95% CI	p value	HR	95% CI	p value
Δ ln(lactate) T1 to T2*	0.20	0.05 to 0.79	0.022	0.20	0.05 to 0.76	0.018
SBP T1 _{per mmHg}	1.00	0.99 to 1.01	0.56	Not in model		0.87
Heart rate T1 _{per beat/minute}	1.01	0.99 to 1.02	0.47	Not in model		0.66
GCS T1 _{per unit}	0.93	0.87 to 0.99	0.034	0.93	0.88 to 0.99	0.022

The variables were simultaneously entered in the model (start model). A backward elimination method was used to construct the final model.
* Δ ln(lactate) T1 to T2: for every 63% decrease (100*(1-(1/e)) = 63%) of the lactate level at T2 relative to the level at T1, the hazard of death decreased by 80% (100 (1-HR)) in the final model (95% CI = 24 to 95%). e = 2.71828, GCS = Glasgow Coma Scale, HR = hazard ratio, ln = natural logarithm, SBP = systolic blood pressure, T1 = on arrival of the ambulance on the scene, T2 = just before or on arrival at the emergency department.

ISSN: 1364-8535