Lactate clearance metrics are not superior to initial lactate in predicting mortality in trauma

Purpose: Despite the availability of different lactate clearance (LC) metrics for clinical use, it remains unknown which metric is superior as a clinical predictor for outcome, particularly in trauma patients. This retrospective study compared four previously described metrics of LC and examined the association between LC and outcome in trauma patients. Methods: Lactate values of trauma patients admitted to a level I trauma center between 2010 and 2013 were retrieved from patient records. LC was calculated according to Huckabee, Regnier et al., Billeter et al. and Zhang et al. Patients were categorized as isolated traumatic brain injury (TBI), trauma with TBI, and trauma without TBI. The primary study outcome was in-hospital mortality. Results: 367 trauma patients were eligible for LC calculation. Only LC by Zhang et al. [area under the curve (AUC) > 0.622, p < 0.01], and Billeter et al. (AUC > 0.616, p < 0.05) were predictive for mortality in trauma patients with and without TBI. However, both were equally prognostic as the initial lactate value for in-hospital mortality. The prognostic value of initial lactate and lactate clearance for in-hospital mortality were not found to differ between isolated TBI, polytrauma with TBI, and trauma without TBI. Conclusions: LC metrics based on the methods of Zhang et al. and Billeter et al. predicted mortality in trauma patients, and their prognostic value did not differ between patients with and without TBI. However, initial lactate value was equally prognostic as these LC metrics. Our findings suggest that a single initial lactate measurement may be a more clinically useful tool to predict mortality than the calculation of lactate clearance.