Association between 24-Hour Lactate Fluctuation and 28-Day Mortality in Patients with Sepsis-Associated AKI: A MIMIC-IV Database Analysis

Background Lactate can be used as a biomarker for the diagnosis and risk stratification of patients with sepsis, and it can be used as a target reference for treatments such as fluid resuscitation, although the potential of the change of lactate over 24 hours for SA-AKI remains uncertain. Methods This retrospective study included patients with sepsis who met the criteria in the Critical Care Medical Information Market (MIMIC-IV) database. Capture, clean, and analyze relevant baselines. Participants had complete data on fluctuation in lactate, creatinine, and cause of death over a 24-hour period. K-M survival curve, Cox proportional hazards regression and Lasso regression models were used to evaluate the relationship between lactate change within 24 hours and 28-day all-cause mortality. Limiting cubic spline regression is applied to estimate possible nonlinear associations. ROC analysis and subgroup analyses were performed to assess predictive value and explore the significance of the 24-hour change of lactate in different populations. Results A total of 5,446 patients with sepsis-associated acute kidney injury (SA-AKI) were enrolled in this study and were divided into four groups according to preset stratification. By analyzing demographic, clinical and prognostic data, 24-hour lactate fluctuation was a valid predictor of 28-day mortality in patients with sepsis and AKI, and decreased lactate clearance was significantly associated with mortality and days of CRRT use. In clinical practice, dynamic monitoring of lactate fluctuation, combined with tools such as SOFA scores, can be used to identify high-risk patients early and optimize treatment strategies, so as to improve prognosis. Conclusions The 24-hour lactate change rate is an effective predictor of 28-day ICU mortality for sepsis patients with acute kidney injury. A lower lactate clearance rate is significantly linked to higher mortality and more CRRT days. Combining lactate change monitoring with SOFA scores and other tools can help identify high-risk patients early, optimize treatment, and improve outcomes.