Preoperative hyperlactatemia and early mortality after liver transplantation: selection of important variables using random forest survival analysis

Abstract

Background: Generally, lactate levels > 2 mmol/L represent hyperlactatemia, whereas lactic acidosis is often defined as lactate > 4 mmol/L. Although hyperlactatemia is common finding in liver transplant (LT) candidates, association between lactate and organ failures with Acute-on-chronic Liver Failure (ACLF) is poorly studied. We searched the important variables for pre-LT hyperlactatemia and examined the impact of preoperative hyperlactatemia on early mortality after LT. Methods: A total of 2,002 patients from LT registry between January 2008 and February 2019 were analyzed. Six organ failures (liver, kidney, brain, coagulation, circulation, and lung) were defined by criteria of EASL-CLIF ACLF Consortium. Variable importance of preoperative hyperlactatemia was examined by machine learning using random survival forest (RSF). Kaplan-Meier Survival curve analysis was performed to assess 90-day mortality.Results: Median lactate level was 1.9 mmol/L (interquartile range: 1.4, 2.4 mmol/L) and 107 (5.3%) patients showed > 4.0 mmol/L. RSF analysis revealed that the four most important variables for hyperlactatemia were MELD score, circulatory failure, hemoglobin, and respiratory failure. The 30-day and 90-day mortality rates were 2.7% and 5.1%, whereas patients with lactate > 4.0 mmol/L showed increased rate of 15.0% and 19.6%, respectively. Conclusion: About 50% and 5% of LT candidates showed pre-LT hyperlactatemia of > 2.0 mmol/L and > 4.0 mmol/L, respectively. Pre-LT lactate > 4.0 mmol/L was associated with increased early post-LT mortality. Our results suggest that future study of correcting modifiable risk factors may play a role in preventing hyperlactatemia and lowering early mortality after LT.

The combination of arterial lactate level with GCS-pupils score to evaluate short term prognosis in traumatic brain injury: a retrospective study

“…Generally, hyperlactatemia is defined as lactate levels > 2 mmol/L, whereas lactic > 4 mmol/L represents acidosis [ 9 ]. But in this study we used 5 mmol/l as the second grading criteria.…”

“…Thus, the study used GCSP plus lactate score as a new index (GCSP-L) to evaluate the severity of TBI patients. Generally, hyperlactatemia is defined as lactate levels > 2 mmol/L, whereas lactic > 4 mmol/L represents acidosis [9]. But in this study we used 5 mmol/l as the second grading criteria.…”

“…We first constructed a lactate score [ 9 ]. If the lactate concentration was below 2 mmol/L [ 9 ], the lactate score was 0. If it was above 5 mmol/L [ 6 , 10 ], the score was 2.…”

Transarterial Embolization for Active Gastrointestinal Bleeding: Predictors of Early Mortality and Early Rebleeding

“…Lactate level is known to be a useful and rapid tool for assessing severity of disease in critically ill patients [21]. It is also known as a predictor of post-operative infection, cardiopulmonary dysfunction, renal impairment, and increased mortality after elective cardiac surgery [22]; aortic dissection [23]; and liver transplantation [24]. Cellular stress, tissue hypoxemia, infection, and various critical illnesses are triggers for the accumulation of serum lactate [25].…”

“…The median length of stay in intensive care units was 3 (1-6) days. The median length of hospital stay was 12 (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24) days. The median follow-up time was 5 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) months.…”