Utility of the early lactate area score as a prognostic marker for septic shock patients in the emergency department

Background: The current Surviving Sepsis Campaign guidelines recommend the remeasurement of lactate levels if the initial lactate level is elevated; however, the prognostic value of lactate kinetics is limited and inconsistent. We attempted to determine the efficacy of the lactate area score (calculated from repeated lactate measurements during initial resuscitation) as a prognostic marker of septic shock in the emergency department (ED). Methods: We performed a retrospective study of adult patients with septic shock in the ED of a single tertiary medical center. Serial lactate levels were measured five times within 12 hours. We also compared the initial lactate level, maximum lactate level, and lactate area score. The lactate area score was defined as the sum of the area under the curve measured at 2, 4, 6, and 12 hours following the initial measurement. Results: A total of 362 patients were enrolled in this study, and the overall 28-day mortality was 31.8%. The lactate area score of serial lactate levels as well as the initial (median [interquartile range], 4.9 [3.4 to 10.5]; P=0.003) and maximum (7.3 [4.2 to 13.2]; P<0.001) lactate levels were significantly higher in the non-survivor group. However, in multivariate analysis, only the lactate area score (odds ratio, 1.013; 95% confidence interval, 1.007 to 1.019) was significantly associated with 28-day mortality. Conclusions: The early lactate area score may be a possible prognostic marker for predicting the 28-day mortality of adult septic shock patients. Further prospective interventional studies should be conducted to validate our results.