To explore the trajectory of lactate dehydrogenase (LDH) changes and the 28-day mortality risk in patients with sepsis based on the group-based trajectory modeling (GBTM).

Data of 857 adult patients with sepsis in the Medical Information Mart for Intensive Care-Ⅳ were collected. The change trajectories of LDH were constructed and grouped based on GBTM, and the baseline characteristics of each group were compared. The Kaplan-Meier survival curve was used to compare the 28-day cumulative survival rate of each trajectory group, and multivariate Cox proportional hazards regression analysis was applied to evaluate the effects of different LDH trajectories on the 28-day mortality rate of patients with sepsis.

Four LDH trajectories were identified through GBTM: a low-level stable group (trajectory 1, 166 cases), a high-level rapid decline group (trajectory 2, 145 cases), a low-level slow decline group (trajectory 3, 286 cases), and a medium-level slow decline group (trajectory 4, 260 cases). Patients in each group were evaluated in terms of heart rate, respiratory rate, diastolic blood pressure, simplified acute physiology score Ⅱ, sequential organ failure assessment score, red blood cells, red blood cell distribution width, hematocrit, hemoglobin, white blood cells, creatinine, urea nitrogen, alanine aminotransferase, aspartate aminotransferase, bilirubin, lactic acid, international normalized ratio, prothrombin time, activated partial thromboplastin time, continues renal replacement treatment, heart failure, acute kidney injury, hypertension, respiratory failure, 28-day survival time, and 28-day mortality rate; all above indicators showed statistically significant differences among the four groups (all P < 0.05). The Kaplan-Meier survival curve showed that there was a statistically significant difference in the 28-day cumulative survival rate among the four groups (χ² = 15.595, P = 0.001), and the cumulative survival rate of trajectory 2 was the lowest. Multivariate Cox proportional hazards regression analysis showed that after adjusting confounding variables, the mortality risk in the trajectory 2 [hazard ratio (HR) = 2.000, 95% confidence interval (CI) (1.205, 3.320), P = 0.017] and trajectory 4 [HR = 1.978, 95%CI (1.251, 3.128), P = 0.011] was much higher than that in the trajectory 1.

Specific LDH trajectories (rapid decline at high levels and slow decline at medium levels) are independent predictive factors for 28-day mortality in patients with sepsis (using a low-level stable LDH trajectory as a reference). Longitudinal LDH trajectories are helpful for identifying high-risk patients with sepsis and provide references for prognosis assessment and clinical management.