Association between serum lactate trajectories and short-term mortality in pediatric acute kidney injury patients

OBJECTIVE: Acute kidney injury (AKI) is a life-threatening condition in children. Serum lactate is a critical indicator of oxygen metabolism and tissue hypoperfusion. This study investigated the association between early dynamic lactate trajectories during pediatric intensive care unit (PICU) and 30-day mortality in pediatric patients with AKI. METHODS: This single-center retrospective study included 1056 critically ill children with AKI admitted to the PICU. Multivariable Cox regression and restricted cubic spline (RCS) models were used to evaluate the association between admission lactate levels and 30-day mortality. Latent growth mixture model (LGMM) was used to identify distinct lactate trajectories based on daily measurements during the first four days of admission. Multivariable Cox regression and Kaplan-Meier analysis were then conducted to assess the association between trajectory classes and 30-day mortality. RESULTS: Admission lactate was independently associated with 30-day mortality (HR 1.13, 95% CI 1.08-1.18, p < 0.01), with a monotonic dose-response relationship (p for non-linearity = 0.46). Three distinct lactate trajectories were identified: Class 1 (high decreasing group, 5.11%), Class 2 (low stable group, 92.05%), and Class 3 (persistent high group, 2.84%). Compared with Class 2, both Class 1 (HR 3.37, 95% CI 1.83-6.24, p < 0.01) and Class 3 (HR 6.24, 95% CI 2.95-13.17, p < 0.01) were associated with significantly increased mortality. Kaplan-Meier curves confirmed the poorest survival in Class 3. CONCLUSION: Both admission lactate level and early dynamic lactate trajectory provide valuable prognostic information in pediatric AKI patients. Identifying lactate patterns facilitates early risk stratification and guides individualized management.