Peak serum lactate as a robust predictor of imminent death in life-sustaining treatment decisions: A study of 73,927 patients.

Objective: The physician order for life-sustaining treatment has been implemented in clinical practice for several years. However, the determination that a patient is in the terminal phase of life, a prerequisite for the withdrawal of life-sustaining treatment, lacks objective criteria. This study aimed to evaluate whether hyperlactatemia could serve as a reliable objective indicator for determining the terminal phase.

Methods: In this retrospective cohort study, we included 73,927 patients admitted to our institution from 2018 to 2023 who had at least one blood lactate measurement. We collected data on the highest blood lactate level measured during hospitalization, mortality, medical department, and intensive care unit (ICU) details. The primary endpoint was 30-day mortality, and we analyzed how well the highest lactate level during hospitalization predicted 30-day mortality across different age groups, medical departments, and ICUs.

Results: Among the patients, 5493 died within 30 days of the maximum lactate measurement. The area under the receiver operating characteristic curve (AUROC) for predicting 30-day mortality based on the maximum lactate level was 0.870 (95% confidence interval [CI] 0.865-0.875) in all patients, indicating high accuracy. Setting the cutoff for the maximum lactate level at 20 mmol/L resulted in a precision of 87% and specificity of 99.8%. Subgroup analyses by age, medical department, and ICU yielded consistent results.

Conclusions: Severe hyperlactatemia during hospitalization showed high precision and specificity for predicting 30-day mortality across various patient groups. These findings suggest that hyperlactatemia could serve as an objective auxiliary indicator for determining the terminal phase, potentially improving consistency in end-of-life decision-making in clinical practice.