Lactate clearance as a predictor of mortality in trauma patients.

BACKGROUND: Initial serum lactate has been associated with mortality in trauma patients. It is not known if lactate clearance is predictive of death in a broad cohort of trauma patients.

METHODS: We enrolled 4,742 trauma patients who had an initial lactate measured during a 10-year period. Patients were identified via the trauma registry. Lactate clearance was calculated at 6 hours. Multivariable logistic regression was used to identify the independent contribution of both initial lactate and lactate clearance with mortality, after adjustment for severity of injury.

RESULTS: Initial lactate level was strongly correlated with mortality: when lactate was less than 2.5 mg/dL, 5.4% (95% confidence interval [CI], 4.5-6.2%) of patients died; with lactate 2.5 mg/dL to 4.0 mg/dL, mortality was 6.4% (95% CI, 5.1-7.8%); with lactate 4.0 mg/dL or greater, mortality was 18.8% (95% CI, 15.7-21.9%). After adjustment for age, Injury Severity Score (ISS), Glasgow Coma Scale (GCS) score, heart rate, and blood pressure, initial lactate remained independently associated with increased mortality, with adjusted odds ratios of 1.0, 1.5 (95% CI, 1.1-2.0) and 3.8 (95% CI, 2.8-5.3), for lactate less than 2.5 mg/dL, 2.5 mg/dL to 4.0 mg/dL, and 4.0 mg/dL or greater, respectively. Among patients with an initially elevated lactate (≥4.0 mg/dL), lower lactate clearance at 6 hours strongly and independently predicted an increased risk of death. For lactate clearances of 60% or greater, 30% to 59%, and less than 30%, the adjusted odds ratio for death were 1.0, 3.5 (95% CI 1.2-10.4), and 4.3 (95% CI, 1.5-12.6), respectively.

CONCLUSION: Both initial lactate and lactate clearance at 6 hours independently predict death in trauma patients.

LEVEL OF EVIDENCE: Prognostic study, level III.