Lactate clearance is a useful biomarker for the prediction of all-cause mortality in critically ill patients: a systematic review and meta-analysis*.

OBJECTIVES: Lactate clearance has been widely investigated for its prognostic value in critically ill patients. However, the results are conflicting. The present study aimed to explore the diagnostic accuracy of lactate clearance in predicting mortality in critically or acutely ill patients. DATA SOURCES: Databases of Medline, Embase, Scopus, and Web of Knowledge were searched from inception to June 2013. STUDY SELECTION: Studies investigating the prognostic value of lactate clearance were defined as eligible. The searched item consisted of terms related to critically ill patients and terms related to lactate clearance. DATA EXTRACTION: The following data were extracted: the name of the first author, publication year, subjects and setting, mean age of study population, sample size, male percentage, mortality of study cohort, definition of clearance, and the initial lactate level. Relative risk was reported to estimate the predictive value of lactate clearance on mortality rate, with relative risk less than 1 indicating that lactate clearance was a protective factor. Meta-analysis of diagnostic accuracy of lactate clearance in predicting mortality was performed by using hierarchical summary receiver operating characteristic model. DATA SYNTHESIS: A total of 15 original articles were included in the study. Because of the significant heterogeneity across studies (I = 61.4%), random-effects model was used to pool relative risks. The pooled relative risk for mortality was 0.38 (95% CI, 0.29-0.50). The overall sensitivity and specificity for lactate clearance to predict mortality were 0.75 (95% CI, 0.58-0.87) and 0.72 (95% CI, 0.61-0.80), respectively. The diagnostic performance improved slightly when meta-analysis was restricted to ICU patients, with sensitivity and specificity of 0.83 (95% CI, 0.67-0.92) and 0.67 (95% CI, 0.59-0.75), respectively.
CONCLUSION: Our study demonstrates that lactate clearance is predictive of lower mortality rate in critically ill patients, and its diagnostic performance is optimal for clinical utility.