Absolute lactate value vs relative reduction as a predictor of mortality in severe sepsis and septic shock

Purpose: Lactate reduction, a common method of risk stratification, has been variably defined. Among patients with an initial lactate >= 4 mmol/L, we compared mortality prediction between a subsequent lactate > 4 mmol/L to a < 10% and < 20% decrease between initial and subsequent lactate values. Materials and methods: We performed a single-center retrospective study of patients presenting to the emergency department with an initial lactate >= 4 mmol/L and suspected infection. Patients were stratified by lactate reduction using 3 previously identified definitions (subsequent lactate >= 4 mmol/L, and < 10% and < 20% relative decrease in lactate) and compared using multivariable logistic regression. Sensitivity and specificity were compared using McNemar test. Results: A subsequent lactate >= 4 mmol/L and a lactate reduction < 20% were associated with increased in-hospital mortality (odds ratio [OR], 3.18; 95% confidence interval [CI], 1.24-8.16; P=.02 and OR, 3.11; 95% CI, 1.39-6.96; P =. 006, respectively), whereas a lactate reduction b10% was not (OR, 1.13; 95% CI, 0.94-1.34; P =.11). A subsequent lactate = 4mmol/L and a lactate reduction < 20% were more sensitive than a lactate reduction b10% (72% vs 41%, P =.002 and 62% vs 41%, P =.008, respectively) but less specific (57% vs 76%, P <.001 and 67% vs 76%, P =.002, respectively). Conclusions: A subsequent lactate = 4 mmol/L and lactate reduction < 20% were associated with increased in hospital mortality, whereas a lactate reduction < 10% was not. Sensitivity and specificity are different between these parameters. (C) 2016 Elsevier Inc. All rights reserved.