Association of Plasma Lactate Level With 28-day Mortality in Non-elderly and Elderly Sepsis Patients: A Retrospective Cohort Study Based on the Mimic-III Database

Abstract Purpose: The objective of this study is to assess the clinical usefulness of lactate as a predictor of 28-day mortality and the relationship between lactate and 28-day mortality in non-elderly (<65 years) and elderly (≥65 years) sepsis patients who were admitted to an intensive care unit (ICU).Methods: This retrospective study used the Medical Information Mart for Intensive Care Ⅲ, a publicly available database of ICUs. Prognosis was evaluated using receiver operating characteristic (ROC) analysis. Univariate and multivariable binary logistic regression models were used to identify the association lactate with 28-day mortality. We converted continuous variable lactate into a categorical variable based on tri-segment quantile to explore segmentation effects.Results: The average age of 2848 patients was 68.01 years old, and about 55.40% of them were male. The overall 28-day mortality was 30.41%, and the rate in elderly patients was 65.82%. Among non-survivors, the lactate level was significantly greater for the non-elderly than the elderly. Lactate level was positively associated with risk of 28-day mortality of the non-elderly sepsis patients (p for trend < 0.001), but there was no significant association between lactate level and 28-day mortality in the elderly group (p for trend = 0.830). The association between lactate and 28-day mortality for sepsis patients without liver cirrhosis was stronger than for sepsis patients with liver cirrhosis (OR 1.28 vs. OR 1.10, P =0.027).Conclusion: Increased lactate level is associated with higher 28-day mortality in the non-elderly sepsis patients, but there is no significant association between the lactate level and 28-day mortality in the elderly group.